I own it! Disc 2 of Halloweeen has some older features on it like Halloween Unmasked and the commentary track featuring Jamie Lee Curtis, John Carpenter, and Deborah Hill. The TV cut of Halloween II is on a second disc for that film. The TV cut of Halloween I is included in the 15 disc set, but it’s not on disc 2, it’s on the bonus disc for the whole set.

EDIT: Basically, disc 2 has bonus features that have been released previously back in the DVD days, while the new stuff is on disc 1