[drc]

The top photo shows a standard studio cabinet card which would measure about 6 1/2" x 4 1/4." (the standard size for a cabinet card). There's no indication it's anything other than a normal studio portrait, meaning it may very well have not been sold commercially like a trading card, though it is interesting that they are in uniform. Just from the posted scan, it looks legitimate and period.

The cabinet card was a standard style or format of photograph back then, sometimes was used like a premium or trading card (N173 Old Judges, Sporting News) but most were jut normal photographs, including of family portraits. If I had to guess, I would strongly guess this cabinet card falls into the non-commercially issued category. Though I can tell you that 19th century studio cabinets like this of Hall of Famers in minor league uniform are very rare.