Sometimes when I only hear a song live and the title isn't mentioned, I make a likely one up to 'place' the song in my own mind. Maybe that happens more often than we think. I have several songs in two or three different (or not so different) versions under two or three different titles on two or three LPs or CDs.
Sometimes maybe people just don't like the original title, or it isn't what they want to get across. I suspect something like this was the reason the Fureys turned No Man's Land into The Green Fiends of France.