My brother had this happen when re-registering his wb after a couple of years out of rego. It showed up as being already registered in Victoria. Someone had access to rta records to find a number that suited their purposes.
I don't see the point of publishing anymore info than you need to. Only a fool tempts fate when it comes to the net.
Mock me if you like, I don't really give a rats. It sure does suck when your pride and joy disappears though. Been there, done that.