I'm not sure if this is a one time glitch I've stumbled upon or if it can be done multiple times without being suspicious. I have several amex cards and sent an online bank payment to the wrong card (airmiles earning) by mistake and called amex to have the charge switched to the card with an outstanding balance (aeroplan earning). I had been using the aeroplan card and there was no activity/purchases on the airmiles card so it could not have generated any airmiles. Amex transferred the payment from the airmiles card to the aeroplan card at no cost and I got the value of the payment in my airmiles account plus the value of the charges in my aeroplan account. Double points! I was only expecting to get the aeroplan points.