[Mr70]

There were a lot of Chevrolet/Oldsmobile car dealers under the same roof back then.More then any other GM dual brands that I can recall.Sorta like catering both ends of the customer spectrum..young & old.
COPO may have been recognized by Fisher Body for that reason as well,which would explain why this Fisher Body issued sheet shows it...at least during that 1971 Oldsmobile model year.
If they started to see an increase in COPO ordered vehicles,Fisher Body may have adjusted their paperwork to reflect that too.Mass quantities of any GM built emergency,service & fleet vehicles would fall under that.