It seems like it would have to be a pretty huge tank, and well-equipped. Keeping more than one type of anemone has been called "a recipe for disaster" even though you hear of people doing it.
Some will release chemicals (as menioned just now - quick post
) when they sense another anemone close by, while others will actually go after the other and physically attack it. While I haven't seen it happen, I've read a few of these examples - one guy on ReefCentral had pictures of his carpet anemone destroying another species...
So yeah, playing with fire to mix them...