The best answer I can come up with is that if it would essentially be apping a second of an existing character from the same canon, then that would not be something that we could accept here. If they are, however, different characters entirely, that would be acceptable.

For example, if someone wanted to app Priest Set and someone else already played Seto Kaiba in this game, that would be acceptable since, while Seto is a reincarnation of Set, they are two entirely different characters. But if someone wanted to app the exact same character from two alternate timelines, that would not be acceptable.

I hope that properly answers your question...!