diff --git a/CHANGELOG.md b/CHANGELOG.md
index 44719c24..440f9fd5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@ and this project adheres to
 - ♿️(frontend) fix language dropdown ARIA for screen readers #2020
 - ♿️(frontend) fix waffle aria-label spacing for new-window links #2030
 - 🐛(backend) stop using add_sibling method to create sandbox document
+- 🐛(backend) duplicate a document as last-sibling
 
 ## [v4.8.1] - 2026-03-17
 
diff --git a/src/backend/core/api/viewsets.py b/src/backend/core/api/viewsets.py
index d402c91b..a1d13221 100644
--- a/src/backend/core/api/viewsets.py
+++ b/src/backend/core/api/viewsets.py
@@ -1361,7 +1361,7 @@ class DocumentViewSet(
             )
         else:
             duplicated_document = document_to_duplicate.add_sibling(
-                "right",
+                "last-sibling",
                 title=title,
                 content=base64_yjs_content,
                 attachments=attachments,
diff --git a/src/backend/core/tests/documents/test_api_documents_duplicate.py b/src/backend/core/tests/documents/test_api_documents_duplicate.py
index 40760539..15e92273 100644
--- a/src/backend/core/tests/documents/test_api_documents_duplicate.py
+++ b/src/backend/core/tests/documents/test_api_documents_duplicate.py
@@ -123,7 +123,7 @@ def test_api_documents_duplicate_success(index):
         image_refs[0][0]
     ]  # Only the first image key
     assert duplicated_document.get_parent() == document.get_parent()
-    assert duplicated_document.path == document.get_next_sibling().path
+    assert duplicated_document.path == document.get_last_sibling().path
 
     # Check that accesses were not duplicated.
     # The user who did the duplicate is forced as owner
@@ -180,6 +180,7 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     client = APIClient()
     client.force_login(user)
 
+    documents_before = factories.DocumentFactory.create_batch(20)
     document = factories.DocumentFactory(
         users=[(user, role)],
         title="document with accesses",
@@ -187,6 +188,12 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     user_access = factories.UserDocumentAccessFactory(document=document)
     team_access = factories.TeamDocumentAccessFactory(document=document)
 
+    documents_after = factories.DocumentFactory.create_batch(20)
+
+    all_documents = documents_before + [document] + documents_after
+
+    paths = {document.pk: document.path for document in all_documents}
+
     # Duplicate the document via the API endpoint requesting to duplicate accesses
     response = client.post(
         f"/api/v1.0/documents/{document.id!s}/duplicate/",
@@ -212,6 +219,10 @@ def test_api_documents_duplicate_with_accesses_admin(role):
     assert duplicated_accesses.get(user=user_access.user).role == user_access.role
     assert duplicated_accesses.get(team=team_access.team).role == team_access.role
 
+    for document in all_documents:
+        document.refresh_from_db()
+        assert document.path == paths[document.id]
+
 
 @pytest.mark.parametrize("role", ["editor", "reader"])
 def test_api_documents_duplicate_with_accesses_non_admin(role):