What should we do if the muezzin calls the Fajr prayer approximately ten to twenty minutes before its due time: should we pray in the mosque and consider it a supererogatory prayer, then repeat it at home, or should we pray it in congregation at the Quran centers?

If you are certain that the mosque-goers pray before the time of prayer enters, clarify this to them with proof, and alert them that delaying the prayer until everyone is certain the time has entered is imperative for unifying the worshippers, increasing their numbers, and preventing reasons for dispute. If they respond, then adhere to their congregation. If they do not respond, do not pray with them as long as you are certain they pray before the time. In that case, pray in another congregation, or pray yourselves as a group in one of your homes or Qur'an centers, while being careful to avoid anything that incites discord and increases disputes.