The only ones I know about personally are classical recordings made by RCA and Mercury Living Presence, but there are probably more out there. About the only way you might know if the original 3 track master is used is possibly if only the L,C,R tracks are used and there is nothing on the surrounds and LFE, and if you know the master was cut during the 50s / early 60s. The Mercury recordings make it a point to tell you that the recording is in its original mastering format.
Quite honestly though, there's not much listening difference between the center channel being discrete or phantom, but you can experiment to see for yourself. There's certainly no opening up of the heavens and instant audio nirvana by listening to the discrete 3 channel masters, which really makes me suspect the bullshit blurb about the Trinaural processor. The difference between discrete and phantom just ain't that big a deal, imaging or otherwise.