Hello there,
Well, I don't really know if it's a bug or itended like that, but it's in fact possible to create multiple account while with a single mail address. If you use the exact same mail you have the right error that you can't create an account, but using the tag function of mail, you can create another account. (yourmail+smth@xxx.com).
I stay available if you need more detail or an account to check what I mean