Was Cosme McMoon Really Edwin McArthur?

There is mounting evidence that Florence Foster Jenkins' legendary accompanist Cosme McMoon was not Edwin McArthur (as was previously mentioned here) but was in fact Cosme McMunn, who was born in Mexico and changed his name upon moving to New York in the early 20's. Both McArthur and McMoon played for Florence Foster Jenkins, but the story goes that McArthur was fired for chortling in recital, and Jenkins subsequently hired McMoon (among others). ParlorMobster has assembled a list of interesting sources, including the following:

• The mystery of Cosme McMoon (McMunn) and Edwin McArthur: the lost composer(s) of Florence Foster Jenkins from Dark Knight Dramaturgy
• What happened to Cosme McMoon after Florence Foster Jenkins died? on Answers.com from Mark McMunn, grand nephew of Cosme
• Articles collected by Max Murray

Donald Collup also credits Mark McMunn in his documentary Florence Foster Jenkins: A World of Her Own. It appears that Cosme was an avid body-builder, worked as a clerk in a bathhouse, and also enjoyed chess. An excerpt from Collup's documentary:

The evidence on the identity of McMoon presented by Collup, McMunn, and others looks pretty convincing, although still largely circumstantial.

Incidentally, if you're in Hartford this month, you should check out TheaterWorks' Souvenir: A Fantasia on the Life of Florence Foster Jenkins, which runs until May 23 with Edwin Cahill playing the role of Cosme McMoon (reviewed in the Times a few days ago).

Wikipedia lists Florence Foster Jenkins as "an American soprano who became famous for her complete lack of rhythm, pitch, tone, and overall singing ability."