This is a classic case of someone finding a 19thC baseball photo with someone who vaguely resembles a well-known figure (this is easy to do), in this case Comiskey, and then finds a buyer who believes him (also unfortunately easy to do).
This photo also appeared (reproduced microscopically) in the Dec. 2007 issue of Sports Collector's Digest with the same false claims:
http://www.sportscollectorsdigest.co..._cabinet_cards