I cannot remember exactly why, but I also have these two photos in that folder showing the RTEC sockets lined up next to their New Britain equivalents.
I'm guessing we were probably discussing who was OE for RTEC, as it seems they were not a primary manufacturer. (Another one that Private Lugnutz was digging into as they were a military/government contract supplier during WWII, as I recall.)
While the knurling appears similar, obviously the broaching is completely different.