Missed this thread and Val's email to me on it.
The blue tinted cards appear to be strips. The athlete cards found in the 4 on 1 exhibit baseball/boxing/entertainment series can be found on strips. As tough as the exhibits are to find, the strips are way harder. I know of fewer than ten legitimate examples. What are sometimes ID'd as strips are cuts from 4 on 1 exhibits. Here is a legitimate Cobb:
Here is an uncut strip of the boxers:
Unless you have an uncut piece, the only way to tell for sure is to compare stock. That said, anyone who knows exhibit cards will be able to tell the difference in about ten seconds. The strip cards are on a thinner, whiter stock that has a very different feel. The strips also will be very close to the same height because they were issued in ten card horizontal strips. The three shown here are new confirmations. I previously documented all ten boxers and the Cobb and Simmons baseball players. I expect that every baseball player known in the exhibit cards will surface as a strip card some day.
BTW [shameless plug] if anyone wants to own one of the boxers, I consigned some to Heritage that may be in the fall catalog.