[quote=@Oblivion666]
Think it might be because they could teleport slice you teleport slice you and just keep repeating that and getting power back if not more.
[/quote]

[quote=@Silvan Haven]
What's wrong with two people having the same magic?
[/quote]

That doesn't answer his question. He was asking why two people couldn't have the same magic, he didn't mention the scythe.
I think it might be to avoid a bunch of people running around with the same magic.