This is a nice idea : take one of the spare origin stories and assign it to the mask, switching you background story to the new one when you put on the mask or something. There are some issues though, sadly.
Biggest drawback is that people that chose a specific origin story because they wanted to play this one specifically will just keep dismissing the mask and try to find a classic solution. I mean, if you're going to have 4 characters with potentially conflicting stories, why would you want a 5th? If you want to get your chosen origin story resolution, why care for the alternate one ?
Again, it's perfect for single-character party. Still got the possibility of getting personnal stories conflicts while manning only one char. In MP or in a regular party, it may not be that exciting.
We will really have to wait for more informations
