Now I have no experience with maroon clowns, but I have read when it comes to pairing them the smaller fish should be added second. This is due to the fact that they are territorial more than other clowns, and if the smaller clown is established in the tank he will defend his territory possibly to the death, as he most likely won't stand a chance against the larger fish. If the larger fish is established in the tank first, he will bully the new fish for a while but will give up soon as the smaller fish will be more likely to submit.
Just my two cents. I believe I read this in Joyce Wilkerson's book, Clownfish. Or maybe it was in a magazine.
BTW, does anyone read books any more?