add: ignore duplicated targets?

dvc/repo/add.py

@@ -43,7 +43,14 @@ def check_recursive_and_fname(args):
 
 
 def transform_targets(args):
-    args.targets = ensure_list(args.targets)
+    from funcy import count_reps
+
+    counts = count_reps(ensure_list(args.targets))
+    dupes = [key for key, count in counts.items() if count > 1]
+    if dupes:
+        msg = ", ".join(f"[b]{key}[/]" for key in dupes)
+        ui.error_write(f"ignoring duplicated targets: {msg}", styled=True)
+    args.targets = list(counts)
 
 
 def check_arg_combinations(args):

dvc/ui/__init__.py

@@ -61,13 +61,17 @@ def error_write(
         style: str = None,
         sep: str = None,
         end: str = None,
+        styled: bool = True,
+        force: bool = True,
     ) -> None:
         return self.write(
             *objects,
             style=style,
             sep=sep,
             end=end,
             stderr=True,
+            force=force,
+            styled=styled,
         )
 
     def write(

tests/func/test_add.py

@@ -1229,3 +1229,12 @@ def test_add_does_not_remove_stage_file_on_failure(
     assert str(exc_info.value) == exc_msg
     assert (tmp_dir / "foo.dvc").exists()
     assert (tmp_dir / stage.path).read_text() == dvcfile_contents
+
+
+def test_add_ignore_duplicated_targets(tmp_dir, dvc, capsys):
+    tmp_dir.gen({"foo": "foo", "bar": "bar", "foobar": "foobar"})
+    stages = dvc.add(["foo", "bar", "foobar", "bar", "foo"])
+
+    _, err = capsys.readouterr()
+    assert len(stages) == 3
+    assert "ignoring duplicated targets: foo, bar" in err