You guys should know something about how Blockbusters operate:
While [most] every Blockbuster store is owned, operated, and supervised by the national corporation (read: not franchises), and your Blockbuster card will work at any store, the computers between stores don't talk to each other. That is, the only time the computer you are checking out at requests info from anywhere other than the local database (and I have reason to believe this is via modem -- scary) is when you present your card at a store that you have never rented from before. For all intents and purposes you are only a member at that store. Do remember, though, that you can't rack up late fees at one store and then skip over to the next one. They will get you.
I think what I'm basically trying to say is that 40 copies of the same coupon will work at all 40 Blockbusters in town.