Going to agree with Elegance on this one, have a very strong feeling that the Clarkii pair would have their way with the percs.
A while ago I have a 3 stripe damsel in my 75 with a Clarkii pair, it was only allowed to be in one corner of the tank, if it strayed out of that area both Clarkiis would go after it. And a 3 striped doesn't look that much like another clown, but close enough for them.