O-Pee-Chee Blank Back Cards
I have a question regarding O-Pee-Chee blank back cards. I collect 1980's O-Pee-Chee Hockey, and I occasionally see cards with blank backs. These are not the cards that are cut from box bottoms, but look just like the regular issue cards. My question is how did these cards come about, were they misprints from factory that were issued in wax pack or were they some type of promo card that was released before the regular cards came out. I see blank backs come up on eBay and just don't know anything about them. I know Beckett grades them but not sure about PSA.