I mean a clone or, at least, a partial clone in some manner. Moving Core from one machine to another wouldn’t result in what you’re seeing. People do that all the time.
I once cloned one RPi to another and got somewhat the same confused results as you have.
Roon identifies the machines it’s running on with unique ids and when you clone one to another the new machine ends up with the same non-unique id.
De-install Roon from one machine, of your choosing, and re-install it. Make sure you get all the Roon pieces. See if that makes a difference.