case 6227 check out this stamp.

[Jamfish50]

I was cleaning my knifes with semi-crome when I notice the stamp it looks stamped underneath the stamp as well strange what do you guys think.jamfish50

[Elvis]

It does look like there is another stamp underneath the Case tang stamp. Can you tell what it says? Also, by looking at the center pin, since it isn't spun it leads me to think the knife has been apart since it left the factory.

[woseyjales]

Bob, reckon the ole stampin' machine had a hiccup and it's simply
a double stamped tang? Ya know, wham wham then spit it out.
3rd pic does seem to show the rare & elusive seldom seen U.8.A. stamp.

Jam, notice you mention using semi-chrome for PK cleanup duty.
You might like to try Mother's mag & aluminum polish (05100)
instead since it is non abrasive, less likely to leave fine polishing
lines on bolsters. Can find it at most discount store automotive depts
cheaper than auto supply stores. On heavy tarnish I may have to
use the metal glo with a damp cloth to reduce abrasiveness.
Metal glo on dry cloth reserved for most stubborn spots.
I've found starting with the most gentle cleaning method 1st
(Renwax) then moving up the 'strength' chain (Mother's, metalglo
damp, metalglo dry, 600 grit, 400 grit, sandblaster) as needed for
desired result seems to be an effective system.
Just thought I'd mention it, even if you already discovered this on
your own might help somebody else w/their kanifery care regimen.