diff --git a/backend/app/channels/manager.py b/backend/app/channels/manager.py
index e8dbbed743..5d309e1eed 100644
--- a/backend/app/channels/manager.py
+++ b/backend/app/channels/manager.py
@@ -1243,13 +1243,18 @@ def _extract_artifacts(result: dict | list, *, thread_id: str | None = None) ->
             break
         # Look for AI messages with present_files tool calls
         if msg.get("type") == "ai":
+            message_paths: list[str] = []
             for tc in msg.get("tool_calls", []):
                 if isinstance(tc, dict) and tc.get("name") == "present_files":
                     args = tc.get("args", {})
                     paths = args.get("filepaths", [])
                     if isinstance(paths, list):
-                        artifacts.extend(p for p in paths if isinstance(p, str))
-    return artifacts
+                        message_paths.extend(p for p in paths if isinstance(p, str))
+            # The scan runs newest-first; prepend so earlier calls stay first.
+            artifacts[:0] = message_paths
+    # Match the ``merge_artifacts`` reducer: first-presented order, no repeats,
+    # so a file presented twice in one turn is uploaded once.
+    return list(dict.fromkeys(artifacts))
 
 
 def _is_hidden_human_control_message(msg: Mapping[str, Any], *, thread_id: str | None = None) -> bool:
diff --git a/backend/tests/test_channels.py b/backend/tests/test_channels.py
index 179952a084..505eca0cfe 100644
--- a/backend/tests/test_channels.py
+++ b/backend/tests/test_channels.py
@@ -7511,6 +7511,58 @@ class TestExtractArtifacts:
         }
         assert _extract_artifacts(result) == ["/mnt/user-data/outputs/a.txt", "/mnt/user-data/outputs/b.csv"]
 
+    def test_multiple_calls_keep_presentation_order_and_deduplicate(self):
+        """A file presented twice in one turn is delivered once, in the order presented.
+
+        ``present_files`` relies on the ``merge_artifacts`` reducer, which keeps
+        first-presented order and drops repeats; the IM reply must match it.
+        """
+        from app.channels.manager import _extract_artifacts
+
+        result = {
+            "messages": [
+                {"type": "human", "content": "chart then report"},
+                {
+                    "type": "ai",
+                    "content": "",
+                    "tool_calls": [{"name": "present_files", "args": {"filepaths": ["/mnt/user-data/outputs/chart.png"]}}],
+                },
+                {"type": "tool", "name": "present_files", "content": "Successfully presented files"},
+                {
+                    "type": "ai",
+                    "content": "",
+                    "tool_calls": [
+                        {"name": "present_files", "args": {"filepaths": ["/mnt/user-data/outputs/report.md", "/mnt/user-data/outputs/chart.png"]}},
+                    ],
+                },
+                {"type": "tool", "name": "present_files", "content": "Successfully presented files"},
+                {"type": "ai", "content": "Done."},
+            ]
+        }
+
+        assert _extract_artifacts(result) == ["/mnt/user-data/outputs/chart.png", "/mnt/user-data/outputs/report.md"]
+
+    def test_single_call_with_repeated_path_delivers_it_once(self):
+        """``merge_artifacts`` also drops repeats inside one ``present_files`` call."""
+        from app.channels.manager import _extract_artifacts
+
+        result = {
+            "messages": [
+                {"type": "human", "content": "send the chart"},
+                {
+                    "type": "ai",
+                    "content": "",
+                    "tool_calls": [
+                        {"name": "present_files", "args": {"filepaths": ["/mnt/user-data/outputs/chart.png", "/mnt/user-data/outputs/report.md", "/mnt/user-data/outputs/chart.png"]}},
+                    ],
+                },
+                {"type": "tool", "name": "present_files", "content": "Successfully presented files"},
+                {"type": "ai", "content": "Done."},
+            ]
+        }
+
+        assert _extract_artifacts(result) == ["/mnt/user-data/outputs/chart.png", "/mnt/user-data/outputs/report.md"]
+
     def test_ignores_hidden_human_control_messages(self):
         """Hidden control messages should not hide current-turn present_files artifacts."""
         from app.channels.manager import _extract_artifacts