Can one Imaam lead multiple Jamaats (congregations) for one Salaah?

In order for a congregation to be valid, the nature of the Imaam’s Salah must correspond with that of the Muqtadi’s (followers) Salaah in all its aspects.

Therefore, if an Imaam had already led a first congregation in a Fardh Salaah, he cannot lead a second congregation of the same Fardh Salaah. The same ruling applies to leading the Jumuah Salaah.

This is because, if an Imaam leads a second congregation of the same Fardh Salaah, the status of the Imaam’s Salaah will be that of a Nafl Salaah as he had already performed his Fardh Salaah. Essentially, the Muqtadi’s (followers) of the second congregation will be performing their Fardh Salaah behind an Imaam who is performing a Nafl Salaah that does not correspond with their Salaah. (Shaami 1/579)

And Allah Ta’ala Knows Best