diff --git a/export_swe_chat.py b/export_swe_chat.py
index da49550..4305404 100644
--- a/export_swe_chat.py
+++ b/export_swe_chat.py
@@ -217,7 +217,12 @@ def attach_first_responses(
             continue
         previous = responses.get(turn.session_id)
         if previous is not None:
-            raise DataError(f"ambiguous assistant response after first prompt in session {turn.session_id!r}")
+            # The dataset can contain multiple transcript rows at one conversational
+            # ordinal. `turn_number` is the documented checked tie-breaker; retain the
+            # earliest actual response and make the condition visible in the funnel.
+            funnel["multipleAssistantResponsesAtFirstResponseOrdinal"] += 1
+            if (turn.turn_number, turn.turn_id) >= (previous.turn_number, previous.turn_id):
+                continue
         responses[turn.session_id] = turn
 
     preliminary: list[Candidate] = []
diff --git a/tests/test_export_swe_chat.py b/tests/test_export_swe_chat.py
index b4f99cf..e747efd 100644
--- a/tests/test_export_swe_chat.py
+++ b/tests/test_export_swe_chat.py
@@ -68,6 +68,18 @@ class ExportSWEChatTests(unittest.TestCase):
         self.assertEqual("answer", value["teacherResponse"])
         self.assertNotIn("answer", value["teacherResponseHash"])
 
+    def test_duplicate_response_ordinal_uses_turn_number_tie_breaker(self):
+        rows = [
+            row("s", "t1", "first", conversation_turn_number=0, turn_number=10),
+            row("s", "t3", "later response", conversation_turn_number=1, turn_number=12, turn_type="assistant_response", role="assistant"),
+            row("s", "t2", "first response", conversation_turn_number=1, turn_number=11, turn_type="assistant_response", role="assistant"),
+        ]
+        candidates, funnel = export_swe_chat.select_candidates(
+            rows, sessions={}, max_per_repo=10, max_per_user=10
+        )
+        self.assertEqual("first response", candidates[0].response_turn.prompt)
+        self.assertEqual(1, funnel["multipleAssistantResponsesAtFirstResponseOrdinal"])
+
 
 if __name__ == "__main__":
     unittest.main()