I always wondered something about that track.
Strummers' vocals sound EXACTLY the same as the solo version on Streetcore. Not "Same guy singing " exactly the same, like "same track" the same. And the version of Redemption Song with both of them wasn't on any of Cash's regualr CD's, just Unearthed, which came out after Strummer died. So, did they just have Cash sing some/all of the song and just splice them together to make it seem like they sang it together?