diff --git a/feedparser/mixin.py b/feedparser/mixin.py
index 3acee1b10..15e32c00c 100644
--- a/feedparser/mixin.py
+++ b/feedparser/mixin.py
@@ -631,9 +631,18 @@ def pop(self, element, strip_whitespace=1):
                 old_value_depth = self.property_depth_map.setdefault(
                     self.entries[-1], {}
                 ).get(element)
-                if old_value_depth is None or self.depth <= old_value_depth:
-                    self.property_depth_map[self.entries[-1]][element] = self.depth
-                    self.entries[-1][element] = output
+                self.property_depth_map[self.entries[-1]][element] = self.depth
+                # Legacy elements are squashed to a singel item
+                legacy_elements = ["title", "summary", "author", "id"]
+                if element in self.entries[-1] and element not in legacy_elements:
+                    previous_output = self.entries[-1][element]
+                    if not isinstance(previous_output, list):
+                        previous_output = [previous_output]
+                    previous_output.append(output)
+                    self.entries[-1][element] = previous_output
+                else:
+                    if old_value_depth is None or self.depth <= old_value_depth:
+                        self.entries[-1][element] = output
                 if self.incontent:
                     contentparams = copy.deepcopy(self.contentparams)
                     contentparams["value"] = output
diff --git a/tests/wellformed/namespace/multiple-elements-with-same-key.xml b/tests/wellformed/namespace/multiple-elements-with-same-key.xml
new file mode 100644
index 000000000..c144342e8
--- /dev/null
+++ b/tests/wellformed/namespace/multiple-elements-with-same-key.xml
@@ -0,0 +1,10 @@
+<!--
+Description:  Ensure multiple elements are parsed into a list
+Expect:       not bozo and entries[0]['madeup_element'] == ['foo', 'bar']
+-->
+<feed xmlns="http://www.w3.org/2005/Atom" xmlns:MadeUp="http://madeup.test">
+	<item>
+		<MadeUp:Element>foo</MadeUp:Element>
+		<MadeUp:Element>bar</MadeUp:Element>
+	</item>
+</feed>
diff --git a/tests/wellformed/node_precedence/atom10_arbitrary_element.xml b/tests/wellformed/node_precedence/atom10_arbitrary_element.xml
index 58598dacc..a163424c8 100644
--- a/tests/wellformed/node_precedence/atom10_arbitrary_element.xml
+++ b/tests/wellformed/node_precedence/atom10_arbitrary_element.xml
@@ -1,18 +1,18 @@
 <!--
 Description: The arbitrarily named node of the least depth should be preferred to those with the same name of greater depth.
-Expect:      not bozo and entries[0]['abcdefg'] == entries[1]['abcdefg'] == 'Correct Value'
+Expect:      not bozo and entries[0]['abcdefg'] == ['Correct Value', 'Incorrect Value'] and entries[1]['abcdefg'] == ['Incorrect Value', 'Correct Value']
 -->
 <feed xmlns="http://www.w3.org/2005/Atom">
 <entry>
   <abcdefg>Correct Value</abcdefg>
   <image>
-	<abcdefg>Incorrect Value</abcdefg>
+    <abcdefg>Incorrect Value</abcdefg>
   </image>
 </entry>
 <entry>
   <image>
-	<abcdefg>Incorrect Value</abcdefg>
+    <abcdefg>Incorrect Value</abcdefg>
   </image>
   <abcdefg>Correct Value</abcdefg>
 </entry>
-</feed>
\ No newline at end of file
+</feed>