Sounds like real but trimmed cards.
The 48s were on a layered stock, and the front layer usually doesn't stand out once the years have let some dust etc get absorbed by the edge of the card.
Most of the 48 set I put together years ago were so bad that the front layer was readily visible on the corners of many cards. Usually the really rare 48 Bowman discs.
Just kidding, they were bad enough that I called them "discs" sometimes.
The highlights were the Berra that had been partly colorized - but with a yellow uniform. several "discs", a few that had been soaked in wax to make them better for some card flipping game, and the usual peeled paper, staple holes, and creases. Maybe 5-6 were fairly nice.
Steve B
Steve B