Harpo's fingers

I'm convinced that for some unknown reason that his hands are doubled by someone else in closeups while playing the harp. Note how super slender the fingers are in the closeup and how much pudgier they appear in longer shots. His fingers are similar to Chico's (watch them playing together on the piano).

Anyone else notice this or know what the backstory may be? Perhaps some MGM exec didn't think Harpo's real fingers were photogenic enough? Stranger things have happened!