As Serena was outside in the forest and practicing a few magic techniques,one of the new ones she would have learned how to do and that would be cloning magic and she would have attempted to test this by trying clone Zwei with it,however the spell backfire a little instead of it effecting Zwei,it would end up effecting  her and splitting her apart into three different versions of herself, one containing  the more cheerful and bubbly side of her while the second carried a little more of the confident and a little bit violent fighting side of her while the last one had her more nervous side