diff --git a/etc/default_data.json b/etc/default_data.json
index 71bb2fe4a..d9a2b5d22 100644
--- a/etc/default_data.json
+++ b/etc/default_data.json
@@ -6639,9 +6639,7 @@
                 {
                     "company_name": "Mirantis",
                     "end_date": "2014-Dec-31"
-                }
-            ],
-            "companies": [
+                },
                 {
                     "company_name": "*independent",
                     "end_date": null
diff --git a/tests/unit/test_config_files.py b/tests/unit/test_config_files.py
index 420cc127e..997dcef35 100644
--- a/tests/unit/test_config_files.py
+++ b/tests/unit/test_config_files.py
@@ -21,6 +21,17 @@ import six
 import testtools
 
 
+def dict_raise_on_duplicates(ordered_pairs):
+    """Reject duplicate keys."""
+    d = {}
+    for k, v in ordered_pairs:
+        if k in d:
+            raise ValueError("duplicate key: %s (value: %s)" % (k, v))
+        else:
+            d[k] = v
+    return d
+
+
 class TestConfigFiles(testtools.TestCase):
     def setUp(self):
         super(TestConfigFiles, self).setUp()
@@ -55,6 +66,19 @@ class TestConfigFiles(testtools.TestCase):
         schema = self._read_file('etc/corrections.schema.json')
         jsonschema.validate(corrections, schema)
 
+    def _verify_default_data_duplicate_keys(self, file_name):
+        try:
+            json.loads(self._read_raw_file(file_name),
+                       object_pairs_hook=dict_raise_on_duplicates)
+        except ValueError as ve:
+            self.fail(ve)
+
+    def test_default_data_duplicate_keys(self):
+        self._verify_default_data_duplicate_keys('etc/default_data.json')
+
+    def test_test_default_data_duplicate_keys(self):
+        self._verify_default_data_duplicate_keys('etc/test_default_data.json')
+
     def _verify_default_data_by_schema(self, file_name):
         default_data = self._read_file(file_name)
         schema = self._read_file('etc/default_data.schema.json')