What is the ruling on someone who prayed Asr twice by mistake, and what is your guidance for whoever mocks that?

Allah has commanded the preservation of congregational prayers in the mosque, and it is not permissible to miss them except for a legitimate excuse. What happened to you, due to oversight and error, carries no sin, for Allah has pardoned mistakes and forgetfulness. Your prayer of Maghrib instead of Asr did not count as Asr for you because you did not intend it as such, nor did it count as Maghrib. The mistake is natural, and your colleagues' mockery might be a jest, so do not be distressed. Remind them of Allah's saying: "O you who have believed, let not a people ridicule [another] people" (Quran 49:11), which prohibits mockery, backbiting, and calling each other by offensive nicknames. And it is sufficient for anyone who does that to recall the Prophet's (peace be upon him) saying: "It is enough evil for a person to belittle his Muslim brother."