Sounds like a creative new way to get locked out of your own keys.
The way I see it, I would want the bio version to be the one on my person. I still have the other put away where it won't be lost.
I lose my hand? Still have a backup. I lose my key? Backup and maybe I have a little bit of extra time to update my bank MFA while the thief figures out the fingerprint situation.
That's been my biggest struggle, I want a primary and backup key but almost every service I use only allows one at a time. I cannot duplicate the same key because it increments internally to avoid replay.