Stevie and sheryl, "Duet", or just backup

[Phoenix]

I know that steve and sheryl have done alot together. and I've heard most of it.
ie. If you ever did believe, Crystal, Sorcerer,ect. "SUPPOSEDLY" stevie "duets" with sheryl crow on Sheryl's song C'mon C'mon, Iv'e listened, and all I hear is backup. I like when sheryl sings backup to stevie, but somehow on this song of sheryls, I was hoping for alittle more. Again "SUPOSEDLY" There is a "DUET" Version of this, but it was only released in Japan .Is this true? Has Anyone heard it? any more thoughts on stevie and sheryl doing duets, or just leaving it as backup to each other?