This track was before officially realised for the tribut-album of Mick Ronson called Heaven and Hull and than for the FM Tribute. But the sax parts of D. Bowie are different from one version to another. Which was the original and which was retake in studio? And was retake by David Bowie? I think the first one but I'm not sure...
Are you sure that Mick Ronson Tribute was released before Freddie's Tribute? Actually Mick played on Freddie's Tribute or maybe it was ghost of Mick...
Remember one thing - the FM Tribute show was originally released on VHS in 1992 and much later on DVD.
I don't think Zizzu means the Mick Ronson tribute, Serry, but the Freddie tribute!
Indeed the version on the Heaven and Hull-album was overdubbed. (By Bowie himself, unless he's fooling us ;-)