Why reinstalling the Companion application creates a new identity.
Each time you reinstall the companion application, a new device is created and entities have to be reassigned.
It goes a little with my other WTH
HA has no way of knowing if the installation is on an old phone or a new phone with the same name.
Some phones can even run multiple OSes, like Samsung with its Knox setup that is splitting the phone into two virtual phones each capable of running a companion app.
I understand, especially since some phones have random MAC addresses.
So it could be done with this WTH.