diff --git a/tests/importing/test_base.py b/tests/importing/test_base.py
index cf49b1c..3d1b153 100644
--- a/tests/importing/test_base.py
+++ b/tests/importing/test_base.py
@@ -473,6 +473,18 @@ class TestImporter(DataTestCase):
             self.assertIs(foo["object"], setting)
             self.assertEqual(foo["data"], {"name": "foo", "value": "bar"})
 
+            # cache should not contain duplicates
+            setting2 = model.Setting(name="foo", value="bar")
+            get_target_objects.return_value = [setting, setting2]
+            cache = imp.get_target_cache()
+            self.assertEqual(len(cache), 1)
+            self.assertIn(("foo",), cache)
+            foo = cache[("foo",)]
+            self.assertEqual(len(foo), 2)
+            self.assertEqual(set(foo), {"object", "data"})
+            self.assertIs(foo["object"], setting2)  # nb. "last" object is kept
+            self.assertEqual(foo["data"], {"name": "foo", "value": "bar"})
+
     def test_get_target_objects(self):
         model = self.app.model
         imp = self.make_importer(model_class=model.Setting)