Original mix with the original sound effects. Most of them have been replaced with modern effects on the Atmos track. There's also directional dialogue on the original mix which was not replicated on the Atmos track.
Here's a strange one. Superman II upgraded to UHD/Dolby Vision/Dolby Atmos the other day on iTunes. A few weeks ago the new transfer showed up in HD/5.1 only. That HD version opened with the "original" WB logo and was silent, as it should be. The UHD/Atmos version plays the modern "As Time Goes...
The best feature of the Superman - The Movie 4K was the Dolby Digital 5.1 audio which was for the 6-track 70mm prints. But it seems that's been dropped from the new pressing.
It's been remixed but for the most part it appears to be the film take. They handle the edit where Superman says, "Hey, look at that" differently, but it was pretty clunky in 1987.
That doesn't make sense. Those sessions were abandoned precisely because things weren't working out. I can't see cash-strapped Cannon doing a pre-dub with unusable material. The last Munich recording date was May 18 and the first English session was May 23.
As someone who has worked on numerous soundtrack projects, and many with WB, that's not how things work. Music would all be kept together. And in the case of this title we know it was because the soundtrack album released in 2008 had access to all of the tapes.
On iTunes it appears Superman III and IV have updated to the new transfers. Both have WB shields closer to the original release and Superman IV has 5.1 audio, which it never had before.
As mentioned, the current disc already has Dolby Vision so there's no change. For this to be a worthwhile visual upgrade, they'd have to fix the orange flash-frame on Christopher Reeve's credit in the opening titles and re-grade other sequences that are lacking on the current disc. Going to...