From what i have found out the pre special edition, THX version DVD's have both a widescreen version of the films and the full screen on the same disc. Wonder if they are letterbox or anamorphic, according to what i read these were Dual Layer DVD's and something of a novelty at the time. Of course now all DVD's or mostly all are DL.
I wonder if they are anamorphic, or if they are just the laserdisc video ported over. The Special Editions came out later.