Is the reward for performing a supererogatory prayer in Quba the same as performing 'Umrah, just like a fard (obligatory) prayer?

It has been authentically established that the Prophet, peace and blessings be upon him, used to visit Quba Mosque and pray two rak'ahs therein. It is a highly recommended Sunnah to visit Quba Mosque, especially on Saturday, with the intention of drawing closer to Allah by visiting it and praying therein. It has been reported that prayer in Quba Mosque is like performing an Umrah, and that whoever purifies himself in his house, then comes to Quba Mosque and prays a prayer therein, will have a reward like that of an Umrah. Also, whoever performs ablution well, then comes to Quba Mosque and performs four rak'ahs therein, will have a reward equal to an Umrah. Therefore, whoever prays two or more rak'ahs in Quba Mosque, whether his prayer is an obligatory one or a supererogatory one, the reward of an Umrah will be written for him.