Is the fast of one who broke it, thinking that the Maghrib Adhan had been called, then it became clear to her that the timing of the Adhan was incorrect, valid or not?

If it is confirmed that the second adhan coincided with sunset, then the fast of that day is not sufficient according to the majority of scholars, though there is an opinion that it is valid. Scholars differ on whether it is obligatory to make up a supererogatory fast if it becomes invalid.