The markings on the mount, although rough, look more like rough finishing rather than trying to removed a stamped serial number. There are rough finish marks all along the surface and around the rear screw hole, etc. It does not appear that a previous serial number has been filed down as I would expect the profile to be altered quite a but to remove a stamped serial number.
I would be more dubious of filing down etc if the rifles 15C serial number was applied to the bracket, but it is in fact a 14C prefix serial number so no attempt to match the bracket to the rifle has been made. Perhaps the previous owner located a 'close enough' Savage serial numbered bracket and left it at that?