I think the second serial number needs more explaining. The adjustable sight overhang covered up serial numbers on some carbines, so it was approved that they could also stamp them on the front of the sight bridge. It didn't take long for the manufacturers to adjust their stamping to move the maker ID and SN farther back so they no longer had to double-stamp. I find it very interesting because the double stamp is fairly rare. I do not believe it adversely affects the value. That's a nice Winchester!