These two guns have the same frame serial number. I believe the all matched gun is made of armorer parts with the original slide from 6675 used as the control. The mismatched gun has the original 6675 frame with mismatched parts.

MATCHED GUN WITH SLIDE SERIAL NUMBER USED AS THE CONTROL AND MADE OF ARMORER PARTS. NOTE: THE EXTRA CUT IN THE SLIDE AND "HUMP" ON THE FRAME

MISMATCHED GUN WITH ORIGINAL FRAME FOR PISTOL 6675. NOTE: FRAME DOES NOT HAVE THE LATER WAR "HUMP" AND THE SLIDE HAS THE DISHED EXTRACTOR CUT OUT