def METHOD_NAME(self, oauth2_clients_test_data, test_app):
    oauth2_client_proto = oauth2_clients_test_data["oauth2_clients"][7]
    resp = test_app.get(f"/admin/oauth2_clients/{oauth2_client_proto.id}/duplicate", status=200)
    resp = resp.form.submit("submit")
    self._check_submission_problem(resp, f"{oauth2_client_proto.client_id} is already used.")