Well you already have Indians fighting British with British allies or several copies of the same nation fighting themselves (and possibly also revolting into the same nations), so having an US while someone else revolts into another US is not a huge problem.
But I DO think especially for US and Mexico and potentially Brazil/Peru/Colombia etc in the future, the revolution should have similar units as the playable faction. Like I see no point of having a comanchero cowboy and a true cowboy, or a “revolutionary sharpshooter” and a true sharpshooter, or a comanchero charros and a chinaco charros, at the same time.