Hi.
first of all the organ is capable of creating such a vast array of tones/sounds the two manuals add to the convinice of moving quickly between or from one sound to another. They alow you to pull out one bright setting for leads and melody while a softer setting for chording.
also it allows you to get a fatter sound by stacking chords in the same octave at times. most people only use one manual as the main and the other for color and texture runs and riffs solo part and so on. but the two together allows you to be as creative soniclly and in harmonics as you can ever imagine. it's like painting a master piece and haveing all the colors of the rainbow at your fiinger tips.
be blessed
