Normally, you only run into mismatched serial numbers on military surplus boltactions. The bolts will be serial numbered (sometimes with only the last 4 digits), and the action will have a serial number. These numbers should match. Collector value is less if it isn't all matching numbers.
This shouldn't even come up with civillian rifles. Was the rifle bought used?
You will get better answers by posting this on thehighroad.org's gun board.
Sorry for my limited help. Good luck.