Yep - twins so often get lumped together by society as if they were a single entity. It can create the most intense hidden jealousy and rivalry if one (or both) want to step out of the other's shadow.
It was only when I thought about it after posting that I can see this one might lead to a couple more posts. After all, Kallicrates will certainly be an interesting king, even though he won't be a good one 😁