diff --git a/server.py b/server.py
index 75359a1..e3994de 100644
--- a/server.py
+++ b/server.py
@@ -316,6 +316,7 @@ class S(BaseHTTPRequestHandler):
                 if 'access' not in data:
                     data['access'] = []
                 data['access'].append(target_user)
+                data['access'] = list(set(data['access']))
                 db.write(f'tests.{test_id}', data)
                 self._set_response(200)
                 self.end_headers()