diff --git a/jedi/inference/value/module.py b/jedi/inference/value/module.py
index 70c86323..fc41d76e 100644
--- a/jedi/inference/value/module.py
+++ b/jedi/inference/value/module.py
@@ -38,6 +38,10 @@ class _ModuleAttributeName(AbstractNameDefinition):
         return compiled.get_string_value_set(self.parent_context.inference_state)
 
 
+def iter_module_names(*args, **kwargs):
+    return sorted(set(iter_module_names(*args, **kwargs)))
+
+
 def iter_module_names(inference_state, paths):
     # Python modules/packages
     for path in paths:
diff --git a/test/test_api/test_project.py b/test/test_api/test_project.py
index 22deaa79..e6d27847 100644
--- a/test/test_api/test_project.py
+++ b/test/test_api/test_project.py
@@ -60,12 +60,12 @@ def test_load_save_project(tmpdir):
 
         ('sample_int', ['helpers.sample_int'], {}),
         ('sample_int', ['helpers.sample_int'], dict(all_scopes=True)),
-        ('sample_int.real', ['builtins.int.real'], {}),
+        ('sample_int.real', ['stub:builtins.int.real'], {}),
 
         ('class sample_int.real', [], {}),
         ('foo sample_int.real', [], {}),
-        ('def sample_int.real', ['builtins.int.real'], {}),
-        ('function sample_int.real', ['builtins.int.real'], {}),
+        ('def sample_int.real', ['stub:builtins.int.real'], {}),
+        ('function sample_int.real', ['stub:builtins.int.real'], {}),
 
         # With modules
         ('test_project.test_search', ['test_api.test_project.test_search'], {}),
@@ -90,8 +90,9 @@ def test_load_save_project(tmpdir):
          dict(complete=True)),
 
         # On sys path
-        ('sys.path', ['sys.path'], {}),
-        ('json.dumps', ['json.dumps', 'json.dumps'], {}),  # stdlib + stub
+        ('sys.path', ['stub:sys.path'], {}),
+        ('json.dumps', ['stub:json.dumps', 'json.dumps'], {}),  # stdlib + stub
+        ('multiprocessing', ['stub:multiprocessing'], {})
     ]
 )
 @pytest.mark.skipif(sys.version_info < (3, 6), reason="Ignore Python 2, because EOL")
@@ -99,4 +100,4 @@ def test_search(string, full_names, kwargs, skip_pre_python36):
     some_search_test_var = 1.0
     project = Project(test_dir)
     defs = project.search(string, **kwargs)
-    assert [d.full_name for d in defs] == full_names
+    assert [('stub:' if d.is_stub() else '') + d.full_name for d in defs] == full_names