GEORGE LIPPERT
There's a reason why photographer Eisenmann photographed a banner instead of the performer.  See below
  George Lippert was born in Germany about 1844 and was active in the American show business for at least eleven years. For all his professional life he was rightly billed as the "only Three-Legged Man on Earth".  It should come as no surprise then, to find that his drawing power began to decrease when another three-legged person, a boy named Francisco Lentini,   arrived in the U.S. in 1898.  In 1899, Mr. Lippert found himself in Salem, Oregon  penniless and homeless and if not for the kindness of a local florist named Mary Riggs who took him in he probably would have perished on the streets of that town.
   For seven years he lived with his benefactor and was visited by many showmen who knew him in his glory days. In the summer of 1906 George Lippert, then 62 years of age,  died of tuberculosis.  An autopsy revealed that he had two hearts and that one heart had died yet he lived another two weeks in that condition. Doctors declared that, even so, he could have continued to live that way if not for the consumption.
   George's third leg was fully formed but somewhat thinner than the other two.  He claimed that he fractured it in a train wreck while in France and that ever since he was not able to use it.  But I'll bet you he never could use it, that it just sort of hung there on his side like the fifth leg of a cow.
   George was certainly exhibiting when Charles Eisenmann was actively photographing Museum freaks so it remains a mystery why he never scheduled a sitting with the famed photographer. 
The reverse side of the above cabinet card
Sometimes, instead of being mulcted of limbs, the abnormal individual is gifted with one limb, or more, in excess of the usual number. For example, a "Three-Legged Man" was exhibited during my stay in Boston, and was pictorially represented as possessing three symmetrical legs in a row, all the three being fashionably attired. Suspecting what the third leg might be, I went to see the man. As I had anticipated, he had a third leg, but it was useless, shriveled, and so small that it could be easily concealed.
Wood, J.G. "Dime Museums," Atlantic Monthly, June 1885; Disability History Museum (12 Janurary 2006)