I wouldn't put them in crates/cages facing each other--I think that would just make them more upset at each other. They'll work it out, mine always did over the decades. Just keep an eye on them, but it's unlikely there will be any damage. My kitties survived Rhodesian Ridgebacks, Golden REtriever and Lab/boxer puppies over the years. Lots of hissing and spitting and lashing out at first.