No, they ported the 5.1 remixes done for mid-90's Dolby ac3 LD releases, but as full bitrate DTS tracks-of course dropping the Surround PCM.
I thought some might be 70mm related, but for example after comparing exhaustively some of us on the lddb forum have concluded that the 5.1 on Die Hard loses the original sound design. I just got the LD myself and the sound is indeed different feeling spatially on the original mix.