you will find that only when the pair is a mateing pair will they host the same anemone at the same time, if they are just paired (getting along) that dosent mean that the female will let the male near her anemone,and if she dose left him in they will be breeding befor to long, alot of times if you have a pair the female will pick hers and the male will take the left over one, but the male is always welcome in her anemone if they are a breeding pair, but when they lay eggs the female will lay the eggs near the males anemone not her own as its the male that broods the eggs, not the female
hope this helps