Hi,
It doesn't use the name but the namekey of the zone which you can't see in the backend. The namekey is geenrated automatically to be unique.
The only reason I could see this would happen with a zone you didn't delete would be if the namekey of the zone starts with a number but that should not be possible because when HikaShop generates the namekey for a new zone, it starts with the type of the zone which is normally a text ( like "shipping", or "country", or "tax", or "state").
So the only reason I could see would be that you imported the zones via your phpmyadmin and filled the namekey with something starting with a number.