You've mixed the story up rather, Diane. The tune Andy Irvine intended to copy (from Child, not Bronson) was Willie O Winsbury, (V, 418); the one he actually got was Fause Foodrage (V, 416). He has always characterised this as a mistake that he only noticed afterwards when it was too late, but he never used to be specific about the 'book of ballads' that he got the tune from (or what song the tune really belonged to). Although I don't imagine for a moment that I was the first person who took the trouble to work out what it was, I do seem to have been the first to give the details on the Internet.

Word has spread in the years since then, though as usual the details have sometimes become confused. I should mention that that business about the page flipping over was purely my speculation as to how it may have happened (similar things have happened to me); so far as I know, Irvine has never said that himself.

On the general topic, it is absolutely normal for songs and tunes transmitted aurally to acquire variant or completely new titles in the course of transmission. There isn't anything surprising about that, except perhaps when one first notices.