The serial number is required only to be on one specific location as determined by the manufacturer, usually (but not always) on the frame. On .22 Ruger automatics, for example, the serial number is on the receiver (the part the barrel screws into), not on the grip frame.
There is no requirement for multiple serial numbers, but many manufacturers have placed the number in hidden places, like on a revolver cylinder or the barrel. That reduces the chance that obliterating the most obvious serial number will make the gun unidentifiable.
So, your gun can be an older S&W, and the "hidden" serial can be on the cylinder.
AFAIK, there is no national registry of stolen guns to which NICS or anyone else has access, and in fact NICS does not have the serial number of the gun being transferred, only whether it is a rifle, shotgun or handgun. State and local authorities sometimes keep records of stolen guns, though.
Some anti-gun groups tout gun registration as being the key to "a total elimination of violent crime" (to quote one such group), but outside the world of fantasy, obliterating the serial number is pointless except in the rare cases where the gun can be traced directly to a criminal. If the gun is stolen, a trace will show only the last legal owner, not the name of the thief or anyone else down the line. Of course, the legal owner is the one the anti-gunners want to imprison - for the crime of owning a gun; they don't care about murderers or robbers.
Jim
P.S. Before I get sniped at, yes, I know there are other locations, but I see no reason to help anyone with an evil mind to locate them. What I wrote is OK for a work of fiction.
JK
P.P.S. The Chiappa chip is used for product tracing and inventory BEFORE sale. Like the famous mattress tag, it can easily and legally be removed by the end customer.
JK