Mine went to the "Pontiac Retail Store", which was the corporate dealership in Pontiac. I don't have the Protect-O-Plate or original invoice, but it likely was an exec car as loaded as it is. It does have a notation on the invoice C M D and a date 2/11/69 with a dollar amount. Retail on the car was $4949.88 and the dollar amount written in is $2045.98.
This makes a lot of sense because the GM exec cars, nowadays, get sold for a lesser price depending on how many miles get put on them by the exec. They call them 'Program Cars'. The time frame between the first and second deliveries is typical for a program car.