the petshop i used to work for had a 120 gal with alot of live rock. a pair of tomatoe clowns ruled the left 3/4th of the tank and a pair of false percs ruled the right 1/4th. conflics did come when food was put in the middle of the tank. otherwise due to the aquascaping, the pairs could not see eachother unless they went beyond their territory.
it can be done, but it can be risky. maroons can be dificult to pair with eachother, i dont think maroons can be mixed with other clowns. but false percs and true percs are fair tempered. plus others.
what really helps is a large tank and visual barriers