Same speicies anemone can group together and can host the same clownfish, my BTA's are proof of that and my two clowns flit between 6 of them that I have seen.
However this guy is trying to keep two different speicies of anemone's together, thus you have two different types of stining celled animals that would definatly compete for space or react when they encounter each other.
The clownfish may perhaps immunize himself for both of them, on that I am not entirely sure of, nor can I speak about what the clown may cause if he were to carry anything back and forth between the two anemonies, If that is what you mean then good question, I'll have to do some research on that.
Thomas