My guess is that it was used internally by Commodore for testing purposes.
(http://sdf.lonestar.org/curiosity/commodore/images/IMG_0360.jpg)
(http://sdf.lonestar.org/curiosity/commodore/images/IMG_0361.jpg)
Those are really interesting boards! I'm in contact with CBM engineers Bil Herd and Dave Haynie, but I believe they came after after the 1980 copyright on those boards. Perhaps they can forward a message to CBM engineer Bob Russell, who would maybe know more about those boards.
Truly,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
Notacon 6 / Blockparty 3 on April 16-19
http://www.notacon.org , http://www.demoparty.us