Ya i agree that we can have microsoft authenticator on multiple devices..
However, I strongly believe that MSFT should do something otherwise we are DEFEATING the whole purpose of backup and recovery.
When I have to set up authenticator app again on the portal, scan the QR-code etc. then why would I bother to do backup and recovery in the first place ??
Almost all my accounts use PUSH NOTIFICATION
So for those accounts backup and recovery is useless.