Many, many years ago I used to illegally double dip, collecting both Eastern and TWA miles for flights on Eastern (you were supposed to get only one or the other, but I "gamed" the system through a scheme that is outdated and useless in today's more automated environment). Ultimately, I used my illegal TWA points for a free room at a Marriott (which used to be one of the TWA rewards back in those days).

I now invite you to pick your own ending to this story, only one of which is correct:

(a) When I returned from my illegally-obtained free stay at the Marriott, I had a sharp pang of regret. I wrote to TWA, confessing what I'd done and offering to reimburse them for the room. The Customer Service Manager wrote back, commending me for my honesty and telling me that they wouldn't charge me anything. He even sent me a $25 travel coupon and urged me to use TWA for my future travel needs, which I did, becoming a fairly loyal customer.

(b) I stayed at the Marriott, drank a toast to TWA for allowing this big gaping loophole to exist for so long, enjoyed our free night thoroughly, and didn't give it another thought until I saw this message thread and wrote this reply.