Can someone explain to me the history of base match prints?

[JoshsOddCollection]

Now that piece is much more interesting

[stevethemagicguy]

Mine also had the watermarks on the back. I never took photos of it but can when its in hand again

[giantsfan5689]

Hi everyone! I know I’m digging up an old thread here, but I have recently acquired one of these! I googled it and this thread was the first hit. Thanks for educating me!