I purchased this copy of "G.I. Joe The Atlantis Factor" for the NES and it has "QA" stamped on the back in a white circle.  I don't buy damaged carts but this isn't really the typical sharpie/sticker type damage.  Is it supposed to be there?  Maybe it was something stamped onto all G.I. Joe products or something?  Does anyone know what it's from?  It's definitely very permanent.

"Quality Assurance" would be my guess. Perhaps it was pulled off the line to test? Either that, or its an internal copy used by game testers to debug.

It very well could be a Quality Assurance stamp of some sort, but I am guessing it is from a private store/rental place putting 'their" stamp on it for ID purposes.
P.S. MY Joe does not have the stamp...

Open it up and see if it has EPROMS possibly? And good thing you don't call that damaged, it's not anything close to bad.

I'm no expert on boards but I opened up the cart and it looks like most of the other boards that I've seen. The label on the front of the cart is identical, as far as I can tell, to the label photograph here at NintendoAGE. I'm inclined now to believe this is a fluke, though it does seem odd. If you guys want me to post a photo of the board just let me know.

You can compare it visually to what a standard board looks like. http://bootgod.dyndns.org:7777/pr...

The board is identical to the one in the link. The mark must be a fluke of some kind.

Or somebody marked it. What would it be a fluke of? It's just a mark, lol.

I had a Madden game with the same mark on the back. Nothing of significance to note about that cart either.

My guess would be that someone had returned it as "non-working", and after the repair centers testing/NOA's testing, they marked it to assure that it was 100% functional. There's another thread on here with Donkey Kong Country 2 with the exact same stamp.