+    def test_cas2_validate_twice(self):
+        response = self._login_user('root', '123')
+        response2 = self._validate_cas2(response, True)
+        user = User.objects.get(username=self.username)
+        self.assertEqual(response2.content, _cas2_sucess_response(user).content)
+
+        response2 = self._validate_cas2(response, True)
+        self.assertEqual(response2.content, _cas2_error_response(INVALID_TICKET).content)
+
+    def test_cas2_validate_twice_with_pgt(self):
+        proxyTarget = "http://my.sweet.service_1"
+        response = self._login_user('root', '123')
+        response2 = self._validate_cas2(response, True, proxyTarget)
+        user = User.objects.get(username=self.username)
+        self.assertEqual(response2.content, _cas2_sucess_response(user).content)
+
+        response2 = self._validate_cas2(response, True, proxyTarget)
+        self.assertEqual(response2.content, _cas2_error_response(INVALID_TICKET).content)
+