What is the ruling on holding two congregational prayers for a single prayer in one mosque unintentionally?

If a group arrives after the regular Imam has finished the prayer, they should pray in a congregation, and there is no harm in that. This is better than an individual praying alone, as the Prophet, peace and blessings be upon him, said: "A man's prayer with another man is purer than his prayer alone, and his prayer with two men is purer than his prayer with one man. And the more numerous they are, the more beloved it is to Allah." The Prophet, peace and blessings be upon him, also encouraged the formation of a second congregation for those who missed the prayer, saying: "Who will give charity to this one by praying with him?" However, establishing two congregations simultaneously is disliked.