Arnie the isolated score track fluctuates in volume depending on the action on-screen; if I'm not correct you can detect this in the 2nd CD of that set. Either way it certainly does not have the fidelity that the actual LP soundtrack (Disc 1) has.
That OST you bought sourced the Disc 2 "film score" FROM that R1 DVD isolated score track -- it's why it raises/lowers in volume, just as the DVD track did.
A little late to the party, but I have an excellent copy of the TV version that's 1st gen off satelitte, if someone ends up doing a Version 2 at some point.
My page is here -- http://www.geocities.com/hockeymandiscs/CINEMA.html