remove duplicates from fee menu

channel_opener_server.go

@@ -107,6 +107,26 @@ func (s *channelOpenerServer) createOpeningParamsMenu(
 	sort.Slice(menu, func(i, j int) bool {
 		return menu[i].MinMsat < menu[j].MinMsat
 	})
+
+	// Remove duplicate items from the menu, keeping the one with the longest validity.
+	var last *lspdrpc.OpeningFeeParams
+	menulen := len(menu)
+	for i := menulen - 1; i >= 0; i-- {
+		current := menu[i]
+		if last != nil {
+			if current.MinMsat == last.MinMsat && current.Proportional == last.Proportional {
+				if current.ValidUntil > last.ValidUntil {
+					// remove last
+					menu = append(menu[:i+1], menu[i+2:]...)
+				} else {
+					// remove current
+					menu = append(menu[:i], menu[i+1:]...)
+				}
+			}
+		}
+
+		last = current
+	}
 	return menu, nil
 }