I'm pretty sure it was only one CD. Keep in mind that the 600MB of CD was just huge at the time, so more than enough place for both versions.
At the time I had only an old 486 with a 500MB disk under DOS, and I played this game quite extensively.
I even remember cutting the sound to gain a few FPS, which enabled me to go from "unplayable" to "barely usable" ^^.