Now seeing these images blown up, I'm definitely leaning more towards "diecut test" pieces.
I didn't notice the serial number before, but that's pretty interesting. I have a couple of theories on what the image is, but my best guess is that it was a photo to show what the diecuts on the cardbacks would look like. It's difficult to say "why" they would do this, and then take a photo of it, but I'm guessing it was for approval by Kenner. I'm guessing they were showing the Kenner guys what a diecut card would look like so they could decide if they wanted to do rounded corners or square corners. Another theory I had is that maybe the three corners are a different angle/cut. I doubt that from looking at a bigger photo, but it could be. Kind of an option 1, 2, 3 or 4 type of thing.
The only other idea I could come up with, and it's a long shot, is that it was an internal printer piece for use in a trade publication. Think of something like a brochure that a printer would hand out to potential clients showing what all the capabilities they could do. That would help explain why it's a photo negative, instead of just a photo, since back in the 70's and 80's before the invention of scanners, you actually had to shoot photos and process the film negatives in order to do page layout. Again, it's a stretch, but not totally out of the question.
I think $300 is a bit of a stretch for it, but it's a cool piece none the less.
