I have never had two bitches together, so wouldn't know. I have never had two dogs together, either. Yet one of each sex has always got along beautifully. My current dog is an only dog, but it was made very clear to me during purchase discussion etc that he generally doesn't like other males, and will rarely tolerate small dogs of either sex.

However, they are all different IMO and have their likes and dislikes of others, just like us humans.