Who Gives A Fish Forums

I'd say it's more likely than not, they'll go to war. Those corals pack a pretty strong sting and are known to be aggressive. You might be alright until they grow close, but they can send out some long sweepers that'll cause damage.

I'd consider checking your lighting and flow levels, see if they're too intense for that particular area. Also, do you have other favias in the tank that might be giving you a clue?