I found a big one.
"Hold On" was sung by 17 different artists, and each one was different. Here's a list of who done it.
The Jonas Brothers
Sons of Champlin
Does it count if it's one letter off? Because I have Miss You by the Rolling Stones and I Miss You by Bjork and Blink-182.
I'm The One - Van Halen, Seether, Mary J. Blige, Static-X, Drake, Danzig, Chamillionaire (lol), and of course, The Descendents.
Alabama Shakes have a Hold On also.