People tend to put value on the rifles based upon what that disk reads, but the disks are sometimes switched between rifles. Even if it is an original disk, people seem to forget that the rifle may have had thousands of rounds put through it since the last time the disk was marked!
Absolutely! I've even heard of people switching discs on rifles in order to 'upgrade' them for selling purposes, as a rifle with a 6.49-6.50 bore and a lower wear rating was supposed to be desirable for a shooter- at the time a person could buy spare discs for $2-3 ea.