Rock in Rio isn't overdubbed per se, but Steve did mandate that Bruce's vocals were "copy-pasted" in some parts to cover where Bruce let the crowd sing (one of the advantages of repeating choruses, I guess). The TV bootleg was widely available so it was pretty clear his performance wasn't otherwise enhanced.
I've never got a hold of the bootleg of the Death on the Road show to compare, but it doesn't sound like there are any obvious overdubs on that album.
I can state pretty definitively that there are no overdubs on Flight 666, having listened to a majority of the bootlegs from that tour. And that the album itself contained noticeable mistakes (like in "Wasted Years", where Adrian hits a wrong note in the intro and Bruce directly comments on it).
Haven't listened enough to En Vivo or the bootleg of that show to decide in that case.