Is there a way to tell? I really can't say for sure. I bought the camera used. I've probably put 30 writes/writes on one of the card and none on the other....
On which camera? I remember reading on the EX1R advertisement that you can, but I haven't tried it myself. (Yep, just checked features at B&H and it says you can. Unfortunately the EX1 is no longer listed there). I'd imagine its in the menu system.