diff --git a/strix/interface/main.py b/strix/interface/main.py
index 373b872f..b19ec78e 100644
--- a/strix/interface/main.py
+++ b/strix/interface/main.py
@@ -37,6 +37,7 @@ from strix.interface.utils import (
     check_docker_connection,
     clone_repository,
     collect_local_sources,
+    dedupe_local_targets,
     find_oversized_local_targets,
     generate_run_name,
     image_exists,
@@ -507,6 +508,8 @@ Examples:
         except ValueError as e:
             parser.error(str(e))
 
+        args.targets_info = dedupe_local_targets(args.targets_info)
+
         assign_workspace_subdirs(args.targets_info)
         rewrite_localhost_targets(args.targets_info, HOST_GATEWAY_HOSTNAME)
 
diff --git a/strix/interface/utils.py b/strix/interface/utils.py
index da1c7081..fbde4c2c 100644
--- a/strix/interface/utils.py
+++ b/strix/interface/utils.py
@@ -1290,6 +1290,31 @@ def build_mount_targets_info(mount_paths: list[str]) -> list[dict[str, Any]]:
     return targets_info
 
 
+def dedupe_local_targets(targets_info: list[dict[str, Any]]) -> list[dict[str, Any]]:
+    """Collapse local_code targets that resolve to the same path.
+
+    When a directory is supplied both as a copied ``--target`` and via
+    ``--mount`` (or as duplicate values of either), keep one entry and prefer
+    the bind-mounted one — so the same tree is never both streamed in and
+    mounted. Order is preserved; non-local targets pass through untouched.
+    """
+    result: list[dict[str, Any]] = []
+    index_by_path: dict[str, int] = {}
+    for target in targets_info:
+        details = target.get("details") or {}
+        path = details.get("target_path")
+        if target.get("type") != "local_code" or not path:
+            result.append(target)
+            continue
+        existing = index_by_path.get(path)
+        if existing is None:
+            index_by_path[path] = len(result)
+            result.append(target)
+        elif details.get("mount") and not (result[existing].get("details") or {}).get("mount"):
+            result[existing] = target  # bind mount supersedes the copied entry
+    return result
+
+
 def _is_localhost_host(host: str) -> bool:
     host_lower = host.lower().strip("[]")
 
diff --git a/tests/test_local_sources.py b/tests/test_local_sources.py
index 4f7f600e..2b0cd2a6 100644
--- a/tests/test_local_sources.py
+++ b/tests/test_local_sources.py
@@ -13,6 +13,7 @@ if TYPE_CHECKING:
 from strix.interface.utils import (
     build_mount_targets_info,
     collect_local_sources,
+    dedupe_local_targets,
     directory_size_bytes,
     find_oversized_local_targets,
 )
@@ -122,3 +123,34 @@ def test_build_mount_targets_info_rejects_empty_path(empty: str) -> None:
     # and silently bind-mount it into the sandbox.
     with pytest.raises(ValueError, match="must not be empty"):
         build_mount_targets_info([empty])
+
+
+def test_dedupe_keeps_distinct_targets_in_order() -> None:
+    targets = [
+        _local_target("/a"),
+        {"type": "web_application", "details": {"target_url": "https://x"}},
+        _local_target("/b", mount=True),
+    ]
+    assert dedupe_local_targets(targets) == targets
+
+
+def test_dedupe_mount_supersedes_copied_same_path() -> None:
+    copied = _local_target("/repo")
+    mounted = _local_target("/repo", mount=True)
+
+    # Copied first, then mounted: the single surviving entry is the mount.
+    result = dedupe_local_targets([copied, mounted])
+    assert len(result) == 1
+    assert result[0]["details"]["mount"] is True
+
+    # Order-independent: mounted first, copied second also yields the mount.
+    result_rev = dedupe_local_targets([mounted, copied])
+    assert len(result_rev) == 1
+    assert result_rev[0]["details"]["mount"] is True
+
+
+def test_dedupe_collapses_duplicate_mounts() -> None:
+    result = dedupe_local_targets(
+        [_local_target("/repo", mount=True), _local_target("/repo", mount=True)]
+    )
+    assert len(result) == 1