...I read that KC used more than one mellotron from time to time so I was wondering if it was a layered sound…
In this video Robert Webb mentions two Mellotrons, but says that Keith recorded the same Mellotron onto two different tracks, then on the mixdown or bounce, he would manually fade between the two recordings to cause motion.
In his EHX demo video, it looks like Bill Rupert uses the Mel9 ORCHESTRA setting to play “In the Court of the Crimson King”, and that sounds dead on.
The sound on Epitaph seems more like the “three violin” Mellotron Strings sound, but mixed as Robert claims Keith did.
So, it seems like you would use the ORCHESTRA setting for “In the Court of the Crimson King” and the STRINGS setting for “Epitaph”.