Spotting these kinds of things is really interesting and, to be honest, I would have never found out the difference in the music. We could certainly discuss the Tavera tracks in more detail but I'm not sure what you mean by lost tracks? Perhaps the parts of the original soundtrack which weren't used in the film? And I've noticed it too that we often appear to be on the same threads.
As for your, theory about the lack of time to make new music , Tavera had already made hew sharptooth music, why not use them instead of the same song twice?
And, Snik, I've noticed that several soundtracks sound different in the film than on the soundtrack. For example, the Southampton track in Horner's Titanic score sounds real different in the film than in the sold soundtrack. However, I'd like to know why.