diff --git a/.changeset/thick-squids-drive.md b/.changeset/thick-squids-drive.md
index 07654da27d..0e798063c0 100644
--- a/.changeset/thick-squids-drive.md
+++ b/.changeset/thick-squids-drive.md
@@ -11,12 +11,15 @@ const TestCard = EntityCardBlueprint.make({
 });
 
 TestCard.override({
-  attachTo: { id: 'something-else', input: 'overriden' },
+  // override attachment points
+  attachTo: { id: 'something-else', input: 'overridden' },
+  // extend the config schema
   config: {
     schema: {
       newConfig: z => z.string().optional(),
     }
   },
+  // override factory
   *factory(originalFactory, { inputs, config }){
     const originalOutput = originalFactory();
 
diff --git a/packages/frontend-plugin-api/src/wiring/createExtension.test.ts b/packages/frontend-plugin-api/src/wiring/createExtension.test.ts
index 547ec2a160..f9e39e98de 100644
--- a/packages/frontend-plugin-api/src/wiring/createExtension.test.ts
+++ b/packages/frontend-plugin-api/src/wiring/createExtension.test.ts
@@ -686,26 +686,6 @@ describe('createExtension', () => {
         },
       });
 
-      const overridden = testExtension.override({
-        output: [numberDataRef, stringDataRef],
-        *factory(originalFactory) {
-          const output = originalFactory();
-          yield* output.omit(numberDataRef);
-
-          yield numberDataRef(output.get(numberDataRef) + 1);
-        },
-      });
-
-      const overridden = testExtension.override({
-        output: [numberDataRef, stringDataRef],
-        *factory(originalFactory) {
-          const output = originalFactory();
-          yield* output;
-
-          yield numberDataRef(output.get(numberDataRef) + 1);
-        },
-      });
-
       const tester = createExtensionTester(overridden);
 
       expect(tester.data(numberDataRef)).toBe(43);
diff --git a/packages/frontend-plugin-api/src/wiring/createExtension.ts b/packages/frontend-plugin-api/src/wiring/createExtension.ts
index 6e75fc76e5..600b96ebe0 100644
--- a/packages/frontend-plugin-api/src/wiring/createExtension.ts
+++ b/packages/frontend-plugin-api/src/wiring/createExtension.ts
@@ -581,7 +581,7 @@ export function createExtension<
               >,
             });
           }
-          return overrideOptions.factory(
+          const parentResult = overrideOptions.factory(
             (innerContext?: {
               config?: {
                 [key in keyof TConfigSchema]: z.infer<
@@ -604,6 +604,13 @@ export function createExtension<
               inputs,
             },
           );
+
+          const deduplicatedResult = new Map<string, UOverrideFactoryOutput>();
+          for (const item of parentResult) {
+            deduplicatedResult.set(item.id, item);
+          }
+
+          return deduplicatedResult.values() as Iterable<UOverrideFactoryOutput>;
         },
       } as CreateExtensionOptions<AnyExtensionDataRef extends UNewOutput ? UOutput : UNewOutput, TInputs & TExtraInputs, TConfigSchema & TExtensionConfigSchema, UOverrideFactoryOutput>);
     },