Wow I didn't know that ocellaris is that aggressive. They supposedly are the friendliest of all clowns. Well I guess it's wrong. Then again those false percs already established their territory. I am not surprised they attacked the maroons.
If you want to put more than one clown together, make sure you have plenty of rocks to hide. Also make sure you introduce them in the same time. And stay away from maroon and tomato, the more aggressive of all clowns.
There is someone I remember, having a maroon, a skunk and a domino damsel, living together in one tank and in one anemone. So it's possible.
stupid_naso