diff --git a/src/lib/mappers/tests/content-item-mapper.test.ts b/src/lib/mappers/tests/content-item-mapper.test.ts
index 2cdd43e..2aac435 100644
--- a/src/lib/mappers/tests/content-item-mapper.test.ts
+++ b/src/lib/mappers/tests/content-item-mapper.test.ts
@@ -179,6 +179,16 @@ describe('ContentItemMapper.addMapping', () => {
       mapper.addMapping(makeItem({ contentID: 10 }), makeItem({ contentID: 21 }))
     ).toThrow('Invalid Mappings detected');
   });
+
+  it('throws when source already has a mapping but a different unmapped target is provided (duplicate mapping attempt)', () => {
+    const mapper = makeMapper();
+    // source 10 is already mapped to target 20
+    mapper.addMapping(makeItem({ contentID: 10 }), makeItem({ contentID: 20 }));
+    // now try to map source 10 to target 99 — target 99 has no mapping, but source already points to 20
+    expect(() =>
+      mapper.addMapping(makeItem({ contentID: 10 }), makeItem({ contentID: 99 }))
+    ).toThrow('Aborting a duplicate mapping attempt');
+  });
 });
 
 // ─── hasSourceChanged ─────────────────────────────────────────────────────────
diff --git a/src/lib/pushers/content-pusher/util/tests/get-content-item-types.test.ts b/src/lib/pushers/content-pusher/util/tests/get-content-item-types.test.ts
index b8ac3b0..96d4c34 100644
--- a/src/lib/pushers/content-pusher/util/tests/get-content-item-types.test.ts
+++ b/src/lib/pushers/content-pusher/util/tests/get-content-item-types.test.ts
@@ -191,6 +191,23 @@ describe('getContentItemTypes — linked items', () => {
     expect(result.linkedContentItems[0]).toBe(linkedItem);
   });
 
+  it('item already in linkedSet is not re-added to normalSet when its own loop iteration runs', () => {
+    // parent is first in the array — when processed, it marks linkedItem as linked
+    // linkedItem comes second — without the fix, its loop iteration would add it back to normalSet
+    const linkedItem = makeItem('linked-ref', 'ModelLinked');
+    const parentItem = makeItem('parent-ref', 'ModelParent', {
+      items: { referenceName: 'linked-ref', fullList: true },
+    });
+
+    const result = getContentItemTypes([parentItem, linkedItem], makeValidOpts());
+    expect(result.linkedContentItems).toHaveLength(1);
+    expect(result.linkedContentItems[0]).toBe(linkedItem);
+    expect(result.normalContentItems).toHaveLength(1);
+    expect(result.normalContentItems[0]).toBe(parentItem);
+    // linkedItem must not appear in normalContentItems
+    expect(result.normalContentItems).not.toContain(linkedItem);
+  });
+
   it('item referenced by multiple parents ends up as linked only once', () => {
     const sharedItem = makeItem('shared-ref', 'ModelShared');
     const parent1 = makeItem('parent-1', 'ModelParent', {