Early, Middle, Late arrangements (22e, 22a, 22)

Three versions of cob #22 have been found, labeled in the photo below as early, middle, and late (as determined by labels). One might think that the “middle” would have been an adaptation of the “early”, and the “late” an adaptation of the “middle”. But the late appears to have notes which occured on the early, and not the middle. Are all of the arrangements based on a single “written” score? Or based on the “early” version?

22, 22a, 22e


Todd Augsburger's Roller Organ Website