Those covers are looking pretty awesome.

As far as the home stereo remixes go, I'm pretty dang certain that only Star Wars was ever really redone in 1985. From the samples that Darth Mallwalker sent me, I didn't detect any differences at all in either Empire or Jedi between the initial laserdisc release and the Japanese Special Collection (aside from the JSC being at a lower level). They are most definitely the exact same mix.

The Special Widescreen Edition of Jedi contains a stereo track that has certainly undergone some remastering, but not remixing. The peak volumes are flattened out and lowered by a couple decibels, which is readily visible from looking at the waveforms; but even with this change, there is very little audible difference from the earlier versions once the higher average volume is accounted for. It is undoubtedly the same mix as before, simply remastered with some slight peak limiting for whatever reason. I haven't heard the SWE for Empire, but if anything was done it probably amounts to no more difference than this, either.

Even the 1985 mix of Star Wars is nearly identical to the original stereo version. The only real change is the inclusion of C-3PO's line about the tractor beam being connected to the main reactor in seven locations, and some apparent widening to the stereo image according to Belbucus. With the sole exception of the one line of dialogue, I don't think they actually 'remixed' anything for this either, simply remastered and processed for better home sound quality.

None of the 35mm mixes have as wide a stereo image as the 70mm and 1993 versions. This is particularly noticeable in the music, and I would hazard a guess that this was probably intended to limit the amount of unwanted sound being sent to the rear channel when upmixed in Dolby Surround.

So it's probably not necessary to include two copies of what is essentially the same mix, for either ESB or RotJ. Even with SW there's not much difference, but there it's justified since there is actual change to the content.