[Gunner]

Hi Mike,
Usually the SN not being in the book means that the records were not located or were so illegible that they could not be recorded. There is a big block of SN where nothing below a D grade was recorded because it was not thought to be worth doing at the time.
What do you mean that there is a 2 stamped below the serial number on both locations? The SN is typically stamped on the side of the lug on all but late Remington guns. I don't recall the SN being stamped on more than one location on a set of barrels.
Pictures of what you are describing would help.
Best Regards,
Erick Dorr

PS A different serial number would mean the barrels came from a different gun. A new second set of factory barrels would have the SN of the gun to which they are fitted stamped with the same serial number as the gun.