I was at Retro Revival yesterday and one of the old Ocean developers (name withheld) told me that the reason all Navy Seals look "used" is because the batch that arrived the day or so before release .. weren't the correct size so all x thousand carts had to be filed down to the correct size. By hand. By the Ocean staff in a 24 hour period ;-)
Fantastic story :D I just looked at my cart and it looks like the edges that go into the machine could have been filed. Not sure the camera picks it up that well but holding it up to the light the first 1mm from the edge looks smoother.
Apparently they were done in shifts. So each cart will be done differently. This might explain why some eBay retailers get accused of selling used Navy Seals games when, as far as they're concerned, they're selling "new old stock".