diff --git a/db-migrations/20260215_fix_duplicate_assigned_dispatches.sql b/db-migrations/20260215_fix_duplicate_assigned_dispatches.sql
new file mode 100644
index 0000000..a4c1b96
--- /dev/null
+++ b/db-migrations/20260215_fix_duplicate_assigned_dispatches.sql
@@ -0,0 +1,216 @@
+-- ================================================================
+-- Migration: Fix Duplicate ASSIGNED Dispatches
+-- Date: 2026-02-15
+-- Description:
+--   - 한 기사가 여러 개의 ASSIGNED 배차를 가지는 문제 해결
+--   - 중복 배차 정리 (가장 최근 배차만 유지)
+--   - 기사 상태(dispatch_status) 동기화
+--   - UNIQUE INDEX 생성으로 중복 방지
+-- ================================================================
+
+BEGIN;
+
+-- ================================================================
+-- Step 1: 백업 테이블 생성 (롤백 및 추적용)
+-- ================================================================
+CREATE TABLE IF NOT EXISTS dispatch_backup_20260215 AS
+SELECT * FROM dispatch
+WHERE status = 'ASSIGNED' AND active = true;
+
+-- 백업된 레코드 수 출력
+DO $$
+DECLARE
+    backup_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO backup_count FROM dispatch_backup_20260215;
+    RAISE NOTICE 'Created backup table with % records', backup_count;
+END $$;
+
+-- ================================================================
+-- Step 2: 중복 데이터 확인 및 로그
+-- ================================================================
+DO $$
+DECLARE
+    duplicate_transporter_count INTEGER;
+    total_duplicate_dispatch_count INTEGER;
+BEGIN
+    -- 중복 배차를 가진 기사 수
+    SELECT COUNT(*) INTO duplicate_transporter_count
+    FROM (
+        SELECT transporter_id
+        FROM dispatch
+        WHERE status = 'ASSIGNED'
+          AND active = true
+          AND transporter_id IS NOT NULL
+        GROUP BY transporter_id
+        HAVING COUNT(*) > 1
+    ) duplicates;
+
+    -- 중복 배차 총 개수
+    SELECT SUM(cnt - 1) INTO total_duplicate_dispatch_count
+    FROM (
+        SELECT COUNT(*) as cnt
+        FROM dispatch
+        WHERE status = 'ASSIGNED'
+          AND active = true
+          AND transporter_id IS NOT NULL
+        GROUP BY transporter_id
+        HAVING COUNT(*) > 1
+    ) dup_counts;
+
+    IF duplicate_transporter_count > 0 THEN
+        RAISE NOTICE '========================================';
+        RAISE NOTICE 'Found % transporters with duplicate ASSIGNED dispatches', duplicate_transporter_count;
+        RAISE NOTICE 'Total % dispatches will be canceled', total_duplicate_dispatch_count;
+        RAISE NOTICE '========================================';
+    ELSE
+        RAISE NOTICE 'No duplicate ASSIGNED dispatches found';
+    END IF;
+END $$;
+
+-- ================================================================
+-- Step 3: 중복 배차 정리 (가장 최근 배차만 유지, 나머지 취소)
+-- ================================================================
+WITH ranked_dispatches AS (
+    SELECT
+        id,
+        transporter_id,
+        assigned_at,
+        ROW_NUMBER() OVER (
+            PARTITION BY transporter_id
+            ORDER BY assigned_at DESC, id DESC  -- 최신 배차 우선
+        ) as rn
+    FROM dispatch
+    WHERE status = 'ASSIGNED'
+      AND active = true
+      AND transporter_id IS NOT NULL
+)
+UPDATE dispatch
+SET
+    status = 'CANCELED',
+    canceled_at = NOW(),
+    updated_at = NOW()
+FROM ranked_dispatches
+WHERE dispatch.id = ranked_dispatches.id
+  AND ranked_dispatches.rn > 1;
+
+-- 취소된 레코드 수 출력
+DO $$
+DECLARE
+    canceled_count INTEGER;
+BEGIN
+    -- 마지막 UPDATE로 영향받은 행 수는 별도 조회 필요
+    SELECT COUNT(*) INTO canceled_count
+    FROM dispatch
+    WHERE status = 'CANCELED'
+      AND canceled_at >= NOW() - INTERVAL '5 seconds';  -- 방금 취소된 것만
+
+    RAISE NOTICE 'Canceled % duplicate dispatches', canceled_count;
+END $$;
+
+-- ================================================================
+-- Step 4: 기사 상태(dispatch_status) 동기화
+-- ================================================================
+
+-- 4-1. ASSIGNED 배차가 없는데 DISPATCH 상태인 기사 찾기
+DO $$
+DECLARE
+    inconsistent_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO inconsistent_count
+    FROM transporters t
+    LEFT JOIN dispatch d ON t.transporter_id = d.transporter_id
+        AND d.status = 'ASSIGNED'
+        AND d.active = true
+    WHERE t.dispatch_status = 'DISPATCH'
+      AND d.dispatch_id IS NULL;
+
+    IF inconsistent_count > 0 THEN
+        RAISE NOTICE 'Found % transporters with inconsistent dispatch_status', inconsistent_count;
+    END IF;
+END $$;
+
+-- 4-2. 기사 상태를 EMPTY로 변경
+UPDATE transporters t
+SET dispatch_status = 'EMPTY'
+WHERE t.dispatch_status = 'DISPATCH'
+  AND NOT EXISTS (
+      SELECT 1 FROM dispatch d
+      WHERE d.transporter_id = t.transporter_id
+        AND d.status = 'ASSIGNED'
+        AND d.active = true
+  );
+
+-- ================================================================
+-- Step 5: 검증 - 중복 데이터가 남아있는지 확인
+-- ================================================================
+DO $$
+DECLARE
+    duplicate_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO duplicate_count
+    FROM (
+        SELECT transporter_id
+        FROM dispatch
+        WHERE status = 'ASSIGNED'
+          AND active = true
+          AND transporter_id IS NOT NULL
+        GROUP BY transporter_id
+        HAVING COUNT(*) > 1
+    ) duplicates;
+
+    IF duplicate_count > 0 THEN
+        RAISE EXCEPTION 'Migration validation failed: Still have % transporters with duplicate assigned dispatches', duplicate_count;
+    ELSE
+        RAISE NOTICE '✓ Validation passed: No duplicate assigned dispatches found';
+    END IF;
+END $$;
+
+-- ================================================================
+-- Step 6: UNIQUE INDEX 생성
+-- ================================================================
+
+-- 기존 인덱스가 있다면 삭제
+DROP INDEX IF EXISTS idx_unique_assigned_transporter;
+
+-- 부분 UNIQUE INDEX 생성
+-- (한 기사는 ASSIGNED 상태 배차를 하나만 가질 수 있음)
+CREATE UNIQUE INDEX idx_unique_assigned_transporter
+ON dispatch (transporter_id)
+WHERE status = 'ASSIGNED' AND active = true;
+
+RAISE NOTICE '✓ Successfully created UNIQUE INDEX: idx_unique_assigned_transporter';
+
+-- ================================================================
+-- Step 7: 인덱스 정보 출력
+-- ================================================================
+DO $$
+DECLARE
+    index_def TEXT;
+BEGIN
+    SELECT indexdef INTO index_def
+    FROM pg_indexes
+    WHERE indexname = 'idx_unique_assigned_transporter';
+
+    RAISE NOTICE '========================================';
+    RAISE NOTICE 'Index definition:';
+    RAISE NOTICE '%', index_def;
+    RAISE NOTICE '========================================';
+END $$;
+
+COMMIT;
+
+-- ================================================================
+-- 마이그레이션 완료 메시지
+-- ================================================================
+DO $$
+BEGIN
+    RAISE NOTICE '========================================';
+    RAISE NOTICE '✓ Migration completed successfully';
+    RAISE NOTICE '========================================';
+    RAISE NOTICE 'Next steps:';
+    RAISE NOTICE '1. Verify data integrity';
+    RAISE NOTICE '2. Monitor application logs for TRANSPORTER_ALREADY_DISPATCHED errors';
+    RAISE NOTICE '3. After 1 week, drop backup table: DROP TABLE dispatch_backup_20260215;';
+    RAISE NOTICE '========================================';
+END $$;
diff --git a/db-migrations/20260215_pre_migration_check.sql b/db-migrations/20260215_pre_migration_check.sql
new file mode 100644
index 0000000..8448f15
--- /dev/null
+++ b/db-migrations/20260215_pre_migration_check.sql
@@ -0,0 +1,218 @@
+-- ================================================================
+-- Pre-Migration Check: Duplicate ASSIGNED Dispatches
+-- Date: 2026-02-15
+-- Description:
+--   마이그레이션 실행 전에 현재 데이터 상태를 확인합니다.
+--   이 스크립트는 데이터를 변경하지 않으며, 읽기 전용입니다.
+-- ================================================================
+
+-- ================================================================
+-- Check 1: 중복 배차를 가진 기사 목록
+-- ================================================================
+SELECT
+    '=== Transporters with Duplicate ASSIGNED Dispatches ===' as check_title;
+
+SELECT
+    t.transporter_id,
+    t.name as transporter_name,
+    t.phone,
+    t.dispatch_status,
+    COUNT(d.dispatch_id) as assigned_count,
+    STRING_AGG(d.dispatch_id::text, ', ' ORDER BY d.assigned_at DESC) as dispatch_ids,
+    STRING_AGG(d.assigned_at::text, ', ' ORDER BY d.assigned_at DESC) as assigned_times,
+    STRING_AGG(d.charge::text, ', ' ORDER BY d.assigned_at DESC) as charges
+FROM dispatch d
+JOIN transporters t ON d.transporter_id = t.transporter_id
+WHERE d.status = 'ASSIGNED'
+  AND d.active = true
+  AND d.transporter_id IS NOT NULL
+GROUP BY t.transporter_id, t.name, t.phone, t.dispatch_status
+HAVING COUNT(d.dispatch_id) > 1
+ORDER BY COUNT(d.dispatch_id) DESC, t.transporter_id;
+
+-- ================================================================
+-- Check 2: 중복 배차 통계
+-- ================================================================
+SELECT
+    '=== Duplicate Dispatch Statistics ===' as check_title;
+
+SELECT
+    COUNT(DISTINCT transporter_id) as transporters_with_duplicates,
+    SUM(duplicate_count - 1) as total_excess_dispatches,
+    MAX(duplicate_count) as max_duplicates_per_transporter,
+    ROUND(AVG(duplicate_count), 2) as avg_duplicates_per_transporter
+FROM (
+    SELECT
+        transporter_id,
+        COUNT(*) as duplicate_count
+    FROM dispatch
+    WHERE status = 'ASSIGNED'
+      AND active = true
+      AND transporter_id IS NOT NULL
+    GROUP BY transporter_id
+    HAVING COUNT(*) > 1
+) dup_stats;
+
+-- ================================================================
+-- Check 3: 기사 상태 불일치 확인
+-- ================================================================
+SELECT
+    '=== Inconsistent Transporter Dispatch Status ===' as check_title;
+
+-- Case 1: ASSIGNED 배차가 있는데 EMPTY 상태인 기사
+SELECT
+    '1. Has ASSIGNED dispatch but status is EMPTY' as inconsistency_type,
+    t.transporter_id,
+    t.name,
+    t.dispatch_status,
+    COUNT(d.dispatch_id) as assigned_dispatch_count
+FROM transporters t
+JOIN dispatch d ON t.transporter_id = d.transporter_id
+WHERE d.status = 'ASSIGNED'
+  AND d.active = true
+  AND t.dispatch_status = 'EMPTY'
+GROUP BY t.transporter_id, t.name, t.dispatch_status
+
+UNION ALL
+
+-- Case 2: ASSIGNED 배차가 없는데 DISPATCH 상태인 기사
+SELECT
+    '2. No ASSIGNED dispatch but status is DISPATCH' as inconsistency_type,
+    t.transporter_id,
+    t.name,
+    t.dispatch_status,
+    0 as assigned_dispatch_count
+FROM transporters t
+LEFT JOIN dispatch d ON t.transporter_id = d.transporter_id
+    AND d.status = 'ASSIGNED'
+    AND d.active = true
+WHERE t.dispatch_status = 'DISPATCH'
+  AND d.dispatch_id IS NULL;
+
+-- ================================================================
+-- Check 4: 중복 배차 상세 정보 (샘플 5건)
+-- ================================================================
+SELECT
+    '=== Sample Duplicate Dispatches (Top 5) ===' as check_title;
+
+SELECT
+    d.dispatch_id,
+    d.transporter_id,
+    t.name as transporter_name,
+    d.status,
+    d.charge,
+    d.start_location,
+    d.destination_location,
+    d.assigned_at,
+    d.created_at,
+    ROW_NUMBER() OVER (PARTITION BY d.transporter_id ORDER BY d.assigned_at DESC) as rank_in_group
+FROM dispatch d
+JOIN transporters t ON d.transporter_id = t.transporter_id
+WHERE d.transporter_id IN (
+    SELECT transporter_id
+    FROM dispatch
+    WHERE status = 'ASSIGNED' AND active = true
+    GROUP BY transporter_id
+    HAVING COUNT(*) > 1
+    LIMIT 5
+)
+AND d.status = 'ASSIGNED'
+AND d.active = true
+ORDER BY d.transporter_id, d.assigned_at DESC;
+
+-- ================================================================
+-- Check 5: 현재 UNIQUE INDEX 존재 여부
+-- ================================================================
+SELECT
+    '=== Current Index Status ===' as check_title;
+
+SELECT
+    indexname,
+    indexdef
+FROM pg_indexes
+WHERE indexname = 'idx_unique_assigned_transporter';
+
+-- 인덱스가 없으면 메시지 출력
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_unique_assigned_transporter') THEN
+        RAISE NOTICE 'INDEX idx_unique_assigned_transporter does not exist';
+    ELSE
+        RAISE NOTICE 'INDEX idx_unique_assigned_transporter already exists';
+    END IF;
+END $$;
+
+-- ================================================================
+-- Check 6: 마이그레이션 영향 예측
+-- ================================================================
+SELECT
+    '=== Migration Impact Estimate ===' as check_title;
+
+SELECT
+    'Total ASSIGNED dispatches' as metric,
+    COUNT(*) as count
+FROM dispatch
+WHERE status = 'ASSIGNED' AND active = true
+
+UNION ALL
+
+SELECT
+    'Dispatches to be canceled (excess)' as metric,
+    COALESCE(SUM(cnt - 1), 0) as count
+FROM (
+    SELECT COUNT(*) as cnt
+    FROM dispatch
+    WHERE status = 'ASSIGNED' AND active = true AND transporter_id IS NOT NULL
+    GROUP BY transporter_id
+    HAVING COUNT(*) > 1
+) dup_counts
+
+UNION ALL
+
+SELECT
+    'Dispatches to remain ASSIGNED' as metric,
+    COUNT(*) - COALESCE((SELECT SUM(cnt - 1) FROM (
+        SELECT COUNT(*) as cnt
+        FROM dispatch
+        WHERE status = 'ASSIGNED' AND active = true AND transporter_id IS NOT NULL
+        GROUP BY transporter_id
+        HAVING COUNT(*) > 1
+    ) dup_counts), 0) as count
+FROM dispatch
+WHERE status = 'ASSIGNED' AND active = true;
+
+-- ================================================================
+-- 최종 요약
+-- ================================================================
+DO $$
+DECLARE
+    dup_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO dup_count
+    FROM (
+        SELECT transporter_id
+        FROM dispatch
+        WHERE status = 'ASSIGNED' AND active = true AND transporter_id IS NOT NULL
+        GROUP BY transporter_id
+        HAVING COUNT(*) > 1
+    ) duplicates;
+
+    RAISE NOTICE '========================================';
+    RAISE NOTICE 'Pre-Migration Check Summary';
+    RAISE NOTICE '========================================';
+
+    IF dup_count > 0 THEN
+        RAISE NOTICE '⚠️  Found % transporters with duplicate ASSIGNED dispatches', dup_count;
+        RAISE NOTICE '✓ Migration is REQUIRED';
+        RAISE NOTICE '';
+        RAISE NOTICE 'Review the results above before proceeding with migration.';
+        RAISE NOTICE 'Execute: 20260215_fix_duplicate_assigned_dispatches.sql';
+    ELSE
+        RAISE NOTICE '✓ No duplicate ASSIGNED dispatches found';
+        RAISE NOTICE '✓ Migration is NOT REQUIRED';
+        RAISE NOTICE '';
+        RAISE NOTICE 'You can still create the UNIQUE INDEX to prevent future duplicates.';
+    END IF;
+
+    RAISE NOTICE '========================================';
+END $$;
diff --git a/db-migrations/20260215_rollback_duplicate_fix.sql b/db-migrations/20260215_rollback_duplicate_fix.sql
new file mode 100644
index 0000000..a8ecf9f
--- /dev/null
+++ b/db-migrations/20260215_rollback_duplicate_fix.sql
@@ -0,0 +1,115 @@
+-- ================================================================
+-- Rollback Script: Revert Duplicate ASSIGNED Dispatches Fix
+-- Date: 2026-02-15
+-- Description:
+--   마이그레이션을 롤백하고 백업에서 데이터를 복원합니다.
+--   ⚠️ 주의: 이 스크립트를 실행하면 중복 데이터가 다시 복원됩니다.
+-- ================================================================
+
+BEGIN;
+
+-- ================================================================
+-- Step 1: 백업 테이블 존재 확인
+-- ================================================================
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'dispatch_backup_20260215') THEN
+        RAISE EXCEPTION 'Backup table dispatch_backup_20260215 does not exist. Cannot rollback.';
+    END IF;
+    RAISE NOTICE 'Backup table found. Proceeding with rollback...';
+END $$;
+
+-- ================================================================
+-- Step 2: UNIQUE INDEX 삭제
+-- ================================================================
+DROP INDEX IF EXISTS idx_unique_assigned_transporter;
+RAISE NOTICE '✓ Dropped UNIQUE INDEX: idx_unique_assigned_transporter';
+
+-- ================================================================
+-- Step 3: 백업에서 데이터 복원
+-- ================================================================
+
+-- 3-1. 마이그레이션으로 취소된 배차 복원
+UPDATE dispatch
+SET
+    status = backup.status,
+    canceled_at = backup.canceled_at,
+    updated_at = backup.updated_at
+FROM dispatch_backup_20260215 backup
+WHERE dispatch.id = backup.id
+  AND dispatch.status = 'CANCELED'
+  AND backup.status = 'ASSIGNED';
+
+-- 복원된 레코드 수 출력
+DO $$
+DECLARE
+    restored_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO restored_count
+    FROM dispatch d
+    JOIN dispatch_backup_20260215 b ON d.id = b.id
+    WHERE d.status = 'ASSIGNED' AND b.status = 'ASSIGNED';
+
+    RAISE NOTICE '✓ Restored % dispatches from backup', restored_count;
+END $$;
+
+-- ================================================================
+-- Step 4: 기사 상태 복원 (필요한 경우)
+-- ================================================================
+
+-- ASSIGNED 배차가 있는데 EMPTY 상태인 기사를 DISPATCH로 변경
+UPDATE transporters t
+SET dispatch_status = 'DISPATCH'
+WHERE t.dispatch_status = 'EMPTY'
+  AND EXISTS (
+      SELECT 1 FROM dispatch d
+      WHERE d.transporter_id = t.transporter_id
+        AND d.status = 'ASSIGNED'
+        AND d.active = true
+  );
+
+-- ================================================================
+-- Step 5: 검증
+-- ================================================================
+DO $$
+DECLARE
+    current_assigned_count INTEGER;
+    backup_assigned_count INTEGER;
+BEGIN
+    SELECT COUNT(*) INTO current_assigned_count
+    FROM dispatch
+    WHERE status = 'ASSIGNED' AND active = true;
+
+    SELECT COUNT(*) INTO backup_assigned_count
+    FROM dispatch_backup_20260215;
+
+    RAISE NOTICE '========================================';
+    RAISE NOTICE 'Rollback validation:';
+    RAISE NOTICE 'Current ASSIGNED dispatches: %', current_assigned_count;
+    RAISE NOTICE 'Backup ASSIGNED dispatches: %', backup_assigned_count;
+
+    IF current_assigned_count = backup_assigned_count THEN
+        RAISE NOTICE '✓ Data restored successfully';
+    ELSE
+        RAISE WARNING 'Data count mismatch. Please verify manually.';
+    END IF;
+    RAISE NOTICE '========================================';
+END $$;
+
+COMMIT;
+
+-- ================================================================
+-- 롤백 완료 메시지
+-- ================================================================
+DO $$
+BEGIN
+    RAISE NOTICE '========================================';
+    RAISE NOTICE '✓ Rollback completed';
+    RAISE NOTICE '⚠️  WARNING: Duplicate ASSIGNED dispatches are now restored';
+    RAISE NOTICE '========================================';
+    RAISE NOTICE 'Next steps:';
+    RAISE NOTICE '1. Verify application behavior';
+    RAISE NOTICE '2. Investigate root cause of migration issues';
+    RAISE NOTICE '3. Plan re-migration strategy';
+    RAISE NOTICE '========================================';
+END $$;
diff --git a/db-migrations/README.md b/db-migrations/README.md
new file mode 100644
index 0000000..26cd5c2
--- /dev/null
+++ b/db-migrations/README.md
@@ -0,0 +1,273 @@
+# Database Migrations
+
+이 디렉토리는 수동으로 실행할 데이터베이스 마이그레이션 스크립트를 포함합니다.
+
+## 📁 파일 목록
+
+| 파일 | 설명 | 실행 순서 |
+|------|------|----------|
+| `20260215_pre_migration_check.sql` | 마이그레이션 전 데이터 상태 확인 (읽기 전용) | 1️⃣ 필수 |
+| `20260215_fix_duplicate_assigned_dispatches.sql` | 중복 배차 정리 + UNIQUE INDEX 생성 | 2️⃣ 필수 |
+| `20260215_rollback_duplicate_fix.sql` | 마이그레이션 롤백 스크립트 | 3️⃣ 선택 (문제 발생 시) |
+
+---
+
+## 🚀 실행 가이드
+
+### Step 1: 사전 체크 (필수)
+
+마이그레이션 실행 전에 **반드시** 사전 체크를 실행하세요.
+
+```bash
+# Docker 환경
+docker exec -i mobility-api-postgres psql -U user -d mobilitydb < db-migrations/20260215_pre_migration_check.sql
+
+# 로컬 PostgreSQL
+psql -U user -d mobilitydb -f db-migrations/20260215_pre_migration_check.sql
+```
+
+**확인 사항**:
+- 중복 배차를 가진 기사 수
+- 취소될 배차 수 (excess)
+- 기사 상태 불일치 여부
+
+### Step 2: 마이그레이션 실행
+
+사전 체크 결과를 확인한 후 마이그레이션을 실행하세요.
+
+```bash
+# Docker 환경
+docker exec -i mobility-api-postgres psql -U user -d mobilitydb < db-migrations/20260215_fix_duplicate_assigned_dispatches.sql
+
+# 로컬 PostgreSQL
+psql -U user -d mobilitydb -f db-migrations/20260215_fix_duplicate_assigned_dispatches.sql
+```
+
+**실행 내용**:
+1. 백업 테이블 생성 (`dispatch_backup_20260215`)
+2. 중복 배차 정리 (최신 배차만 유지)
+3. 기사 상태 동기화
+4. UNIQUE INDEX 생성 (`idx_unique_assigned_transporter`)
+
+### Step 3: 검증
+
+마이그레이션 후 데이터를 검증하세요.
+
+```sql
+-- 중복 배차가 남아있는지 확인
+SELECT transporter_id, COUNT(*)
+FROM dispatch
+WHERE status = 'ASSIGNED' AND active = true AND transporter_id IS NOT NULL
+GROUP BY transporter_id
+HAVING COUNT(*) > 1;
+-- 결과: 0건이어야 함
+
+-- UNIQUE INDEX 생성 확인
+SELECT indexname, indexdef
+FROM pg_indexes
+WHERE indexname = 'idx_unique_assigned_transporter';
+
+-- 기사 상태 일관성 확인
+SELECT t.dispatch_status, COUNT(*)
+FROM transporters t
+LEFT JOIN dispatch d ON t.transporter_id = d.transporter_id
+    AND d.status = 'ASSIGNED' AND d.active = true
+GROUP BY t.dispatch_status, (d.dispatch_id IS NOT NULL);
+```
+
+### Step 4: 애플리케이션 배포
+
+코드 변경사항을 배포하세요.
+
+```bash
+# 빌드
+./gradlew clean build
+
+# 재시작 (Docker Compose)
+docker-compose down
+docker-compose up -d
+
+# 로그 확인
+docker-compose logs -f api
+```
+
+---
+
+## 🔙 롤백 (문제 발생 시)
+
+마이그레이션 후 문제가 발생한 경우에만 실행하세요.
+
+```bash
+# Docker 환경
+docker exec -i mobility-api-postgres psql -U user -d mobilitydb < db-migrations/20260215_rollback_duplicate_fix.sql
+
+# 로컬 PostgreSQL
+psql -U user -d mobilitydb -f db-migrations/20260215_rollback_duplicate_fix.sql
+```
+
+**⚠️ 주의**: 롤백 시 중복 데이터가 다시 복원됩니다.
+
+---
+
+## 📊 마이그레이션 상세
+
+### 중복 배차 정리 전략
+
+**기본 전략**: 가장 최근 배차만 유지, 나머지 취소
+
+```sql
+-- 기사별로 assigned_at 기준 내림차순 정렬
+-- ROW_NUMBER = 1: 유지 (가장 최근)
+-- ROW_NUMBER > 1: 취소
+```
+
+**대안 전략**:
+
+스크립트를 수정하여 다른 전략을 사용할 수 있습니다:
+
+```sql
+-- 옵션 A: 가장 오래된 배차 유지
+ORDER BY assigned_at ASC, id ASC
+
+-- 옵션 B: 가장 큰 요금 유지
+ORDER BY charge DESC, assigned_at DESC
+
+-- 옵션 C: 특정 배차 ID 수동 지정
+WHERE id IN (100, 200, 300)  -- 취소할 배차 ID
+```
+
+### UNIQUE INDEX 상세
+
+```sql
+CREATE UNIQUE INDEX idx_unique_assigned_transporter
+ON dispatch (transporter_id)
+WHERE status = 'ASSIGNED' AND active = true;
+```
+
+**특징**:
+- **부분 인덱스 (Partial Index)**: `status = 'ASSIGNED' AND active = true` 조건만 적용
+- **저장 공간 효율**: 전체 배차가 아닌 ASSIGNED 상태만 인덱싱
+- **성능**: 해당 조건 검색 시 빠른 조회
+
+**효과**:
+- 한 기사는 ASSIGNED 상태 배차를 **하나만** 가질 수 있음
+- 중복 INSERT 시도 시 PostgreSQL 에러 발생
+- 애플리케이션에서 적절히 에러 처리 필요
+
+---
+
+## 🧪 테스트 시나리오
+
+### 1. 중복 배차 방지 테스트
+
+```sql
+-- 기사 1번에게 배차 할당
+UPDATE dispatch SET transporter_id = 1, status = 'ASSIGNED' WHERE dispatch_id = 100;
+
+-- 같은 기사에게 또 다른 배차 할당 시도 (실패해야 함)
+UPDATE dispatch SET transporter_id = 1, status = 'ASSIGNED' WHERE dispatch_id = 200;
+-- ERROR: duplicate key value violates unique constraint "idx_unique_assigned_transporter"
+```
+
+### 2. 정상적인 배차 흐름 테스트
+
+```sql
+-- 1. 기사 1번에게 배차 할당
+UPDATE dispatch SET transporter_id = 1, status = 'ASSIGNED' WHERE dispatch_id = 100;
+
+-- 2. 배차 완료
+UPDATE dispatch SET status = 'COMPLETED' WHERE dispatch_id = 100;
+
+-- 3. 새로운 배차 할당 (성공해야 함)
+UPDATE dispatch SET transporter_id = 1, status = 'ASSIGNED' WHERE dispatch_id = 200;
+```
+
+---
+
+## 📋 체크리스트
+
+마이그레이션 실행 전:
+- [ ] 프로덕션 데이터베이스 백업 완료
+- [ ] `20260215_pre_migration_check.sql` 실행 완료
+- [ ] 중복 배차 데이터 검토 완료
+- [ ] 영업팀 및 기사에게 점검 시간 공지
+- [ ] 애플리케이션 코드 변경사항 준비 완료
+
+마이그레이션 실행 후:
+- [ ] 중복 데이터 제거 확인 (0건)
+- [ ] UNIQUE INDEX 생성 확인
+- [ ] 기사 상태 일관성 확인
+- [ ] 애플리케이션 재시작
+- [ ] API 동작 테스트 (`/api/v1/transporter/current-dispatch`)
+- [ ] 새로운 배차 할당 테스트
+- [ ] 로그에서 `TRANSPORTER_ALREADY_DISPATCHED` 에러 모니터링
+
+1주일 후:
+- [ ] 백업 테이블 삭제 (`DROP TABLE dispatch_backup_20260215;`)
+
+---
+
+## 🛠 트러블슈팅
+
+### Q1. "duplicate key value" 에러 발생 시
+
+**원인**: UNIQUE INDEX 생성 전에 중복 데이터가 제거되지 않음
+
+**해결**:
+```sql
+-- Step 3를 다시 실행하여 중복 제거
+-- 그 후 Step 6의 INDEX 생성 재시도
+```
+
+### Q2. 마이그레이션 실행 중 "Migration validation failed" 에러
+
+**원인**: 중복 데이터가 완전히 제거되지 않음
+
+**해결**:
+```sql
+-- 수동으로 중복 확인
+SELECT transporter_id, COUNT(*)
+FROM dispatch
+WHERE status = 'ASSIGNED' AND active = true AND transporter_id IS NOT NULL
+GROUP BY transporter_id
+HAVING COUNT(*) > 1;
+
+-- 해당 레코드 수동 처리
+```
+
+### Q3. 롤백 후 애플리케이션 에러 계속 발생
+
+**원인**: 코드는 이미 변경되었으나 DB는 롤백됨
+
+**해결**:
+1. 코드를 이전 버전으로 롤백
+2. 또는 마이그레이션을 다시 실행
+
+### Q4. 백업 테이블이 너무 큰 경우
+
+**확인**:
+```sql
+SELECT pg_size_pretty(pg_total_relation_size('dispatch_backup_20260215'));
+```
+
+**삭제**:
+```sql
+-- 1주일 후 안전하게 삭제
+DROP TABLE IF EXISTS dispatch_backup_20260215;
+```
+
+---
+
+## 📞 지원
+
+문제 발생 시:
+1. 로그 확인: `/var/log/postgresql/`, `docker-compose logs -f postgres`
+2. 백업 테이블 확인: `SELECT * FROM dispatch_backup_20260215 LIMIT 10;`
+3. GitHub Issue 생성: [프로젝트 이슈 링크]
+
+---
+
+## 📚 관련 문서
+
+- [CONCURRENT_DISPATCH_ISSUE.md](../CONCURRENT_DISPATCH_ISSUE.md) - 문제 분석 및 해결 방안
+- [CLAUDE.md](../CLAUDE.md) - 프로젝트 아키텍처 및 데이터베이스 구조
diff --git a/src/main/java/com/mobility/api/domain/dispatch/repository/DispatchRepository.java b/src/main/java/com/mobility/api/domain/dispatch/repository/DispatchRepository.java
index 568734a..8da141d 100644
--- a/src/main/java/com/mobility/api/domain/dispatch/repository/DispatchRepository.java
+++ b/src/main/java/com/mobility/api/domain/dispatch/repository/DispatchRepository.java
@@ -82,4 +82,17 @@ List<DispatchDistanceProjection> findDispatchesByDistance(
      * @return 배차 정보
      */
     Optional<Dispatch> findByTransporterIdAndStatus(Long transporterId, StatusType status);
+
+    /**
+     * 특정 기사의 특정 상태 배차 조회 (최신순)
+     * 여러 건이 있을 경우 가장 최근에 할당된 배차 반환
+     * @param transporterId 기사 ID
+     * @param status 배차 상태
+     * @return 가장 최근 배차 정보
+     */
+    @Query("SELECT d FROM Dispatch d WHERE d.transporter.id = :transporterId AND d.status = :status ORDER BY d.assignedAt DESC LIMIT 1")
+    Optional<Dispatch> findFirstByTransporterIdAndStatusOrderByAssignedAtDesc(
+            @Param("transporterId") Long transporterId,
+            @Param("status") StatusType status
+    );
 }
diff --git a/src/main/java/com/mobility/api/domain/dispatch/service/DispatcherService.java b/src/main/java/com/mobility/api/domain/dispatch/service/DispatcherService.java
index 907d05a..78f3feb 100644
--- a/src/main/java/com/mobility/api/domain/dispatch/service/DispatcherService.java
+++ b/src/main/java/com/mobility/api/domain/dispatch/service/DispatcherService.java
@@ -36,18 +36,23 @@ public class DispatcherService {
     @Transactional
     public DispatchAssignCompleteRes assignDispatch(Long dispatchId, Long transporterId) {
 
-        // 1. 기사 정보 조회
-        Transporter transporter = transporterRepository.findById(transporterId)
+        // 1. 기사 정보 조회 (비관적 락)
+        Transporter transporter = transporterRepository.findByIdWithPessimisticLock(transporterId)
                 .orElseThrow(() -> new GlobalException(ResultCode.NOT_FOUND_USER));
 
-        // 2. 배차 정보 조회 -> DB 로우에 락이 걸림
+        // 2. 이미 배차중인 기사인지 체크
+        if (transporter.getDispatchStatus() == DispatchStatus.DISPATCH) {
+            throw new GlobalException(ResultCode.TRANSPORTER_ALREADY_DISPATCHED);
+        }
+
+        // 3. 배차 정보 조회 (비관적 락)
         Dispatch dispatch = dispatchRepository.findByIdWithPessimisticLock(dispatchId)
                 .orElseThrow(() -> new GlobalException(ResultCode.NOT_FOUND_DISPATCH));
 
-        // 3. 배차 할당
+        // 4. 배차 할당
         dispatch.assignDispatch(transporter);
 
-        // 4. 기사의 배차 상태를 DISPATCH로 변경 (배차중인 오더가 있음)
+        // 5. 기사의 배차 상태를 DISPATCH로 변경 (배차중인 오더가 있음)
         transporter.changeDispatchStatus(DispatchStatus.DISPATCH);
 
         return DispatchAssignCompleteRes.from(dispatch);
@@ -178,8 +183,8 @@ public CurrentDispatchDetailRes getCurrentDispatch(Long transporterId) {
             throw new GlobalException(ResultCode.DISPATCH_NOT_ASSIGNED);
         }
 
-        // 3. 기사에게 ASSIGNED 상태로 배차된 오더 조회
-        Dispatch dispatch = dispatchRepository.findByTransporterIdAndStatus(transporterId, StatusType.ASSIGNED)
+        // 3. 기사에게 ASSIGNED 상태로 배차된 오더 조회 (최신순)
+        Dispatch dispatch = dispatchRepository.findFirstByTransporterIdAndStatusOrderByAssignedAtDesc(transporterId, StatusType.ASSIGNED)
                 .orElseThrow(() -> new GlobalException(ResultCode.DISPATCH_NOT_ASSIGNED));
 
         // 4. DTO 변환 및 반환
diff --git a/src/main/java/com/mobility/api/domain/transporter/repository/TransporterRepository.java b/src/main/java/com/mobility/api/domain/transporter/repository/TransporterRepository.java
index 869e29b..dfd37c1 100644
--- a/src/main/java/com/mobility/api/domain/transporter/repository/TransporterRepository.java
+++ b/src/main/java/com/mobility/api/domain/transporter/repository/TransporterRepository.java
@@ -4,10 +4,14 @@
 import com.mobility.api.domain.transporter.TransporterStatus;
 import com.mobility.api.domain.transporter.dto.TransporterDistanceProjection;
 import com.mobility.api.domain.transporter.entity.Transporter;
+import jakarta.persistence.LockModeType;
+import jakarta.persistence.QueryHint;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
 import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.jpa.repository.QueryHints;
 import org.springframework.data.repository.query.Param;
 
 import java.util.List;
@@ -94,4 +98,15 @@ boolean existsEligibleDriversWithinRadius(
     // 2. 상태 필터 적용 조회 (페이징)
     Page<Transporter> findAllByOfficeAndStatus(Office office, TransporterStatus status, Pageable pageable);
 
+    /**
+     * 비관적 락을 사용한 기사 조회 (동시성 제어)
+     * 배차 할당 시 동시에 여러 배차가 같은 기사에게 할당되는 것을 방지
+     * @param transporterId 기사 ID
+     * @return 기사 정보
+     */
+    @Lock(LockModeType.PESSIMISTIC_WRITE)
+    @QueryHints({@QueryHint(name = "jakarta.persistence.lock.timeout", value = "3000")})
+    @Query("SELECT t FROM Transporter t WHERE t.id = :transporterId")
+    Optional<Transporter> findByIdWithPessimisticLock(@Param("transporterId") Long transporterId);
+
 }