You're thinking of Goldsmith's original (before it was edited for final release) score track. That's on the Blu-ray, along with the final release score, but this is another alternate music track that also includes "production sound" (not entirely sure what that constitutes; Darwinsgirl can probably elaborate, as I said, I've not listened to it yet).
I read online that they had wanted to put it on the Anthology, but it simply wouldn't fit on the disc on top of everything else.
The other thing on the Legacy that appears to be unique is the crab-walk scene. I have a feeling it's glimpsed in one of the documentaries in the Anthology, but the full sequence isn't on there separately, not even as part of the LaserDisc archives, so far as I can tell.