What is the ruling on multiple congregations in one mosque at the same time, and with which congregation should the worshiper pray?

If a mosque has a regular Imam, it is disliked to hold another congregational prayer without his permission, as this can lead to disunity, disruption, and potentially animosity.

However, if a mosque does not have a regular Imam, the worshippers should unite behind a single Imam.

Prayer should be performed with the congregation of the regular Imam in the mosque that has one.