Quality HMC with X under serial number.

I recently bought a Quality HMC M1 Carbine on Gunbroker. Buy now price was $1200 so I jumped on it. It is all Quality except barrel and stock. The barrel is a Winchester and the stock is marked RSG in the sling cut out. The RSG has an X stamped over it. Looks like a Quality crossed cannon cartouche on the other side. Some Carbine experts tell me the X under the serial number indicates a duplicate serial number.
https://www.milsurps.com/images/impo...4/QHMCF4-1.jpg
https://www.milsurps.com/images/impo...4/QHMCF7-1.jpg
https://www.milsurps.com/images/impo...04/QHMC6-1.jpg
https://www.milsurps.com/images/impo...4/QHMC51-1.jpg
https://www.milsurps.com/images/impo...4/QHMCF3-1.jpg
https://www.milsurps.com/images/impo...4/QHMCF1-1.jpg
https://www.milsurps.com/images/impo...4/QHMCF2-1.jpg

Mike,

I have your QHMC’s older brother 4696xxx no X on the receiver but does have a Winchester barrel; W 1” behind front sight, a P about 5 ½” behind front sight and a Winchester oval proof about 5/8” in front of a type 1 barrel band. I’m also has a RSG marked stock, No X through the letters and no CC.

The finish on mine is worn thin.

John