What confuses me a bit are the cards over #121 ( I think) that have a different ad on the back for Superman cards. Unless they were printed on a separate sheet as double prints within the first series they seem to be a strange outlier.
I know Bob Lemke wrote about them before, but there doesn't seem to be much more discussion into them.
https://boblemke.blogspot.com/2011/1...n-ad-back.html
Were those printed with the second series?