Thanks for the reply maraud, RCtech, and RobertB.
So if I understand this correctly, the GEOS 128 2.0 software box came with the Commodore 64 GEOS 2.0 manual along with an addendum manual for the Commodore 128. See summary listing below. If this is incorrect, please feel free to comment, correct, or criticize.
English Language Manuals
(Titles taken from the title page.)
Both manuals written by Patricia Huey.
1. GEOS 2.0 User's Manual (307 pages, printed 7/88)
2. GEOS 128 2.0 User's Manual Addendum (106 pages, printed 11/88)