I found a few of these in a lot I got recently. What I find interesting about them, is that, I think, they did not happen at the printing factory. I assume these occurred by having a stack of cards sitting in a very damp/dank place for a very long time. This assumption is based on:
1 - The heavy amount of paper loss, not only on back but also on fronts.
2 - The actual backs and wst don't always match. The most blatant being Marquard with a 350-460 back, but a 350 wst. Also, even though harder to see, both Coles and Stahl have Piedmont backs, but OMSL wst.
Any other theories ?
wst01.jpg
wst02.jpg
Fun, fun
Scott