What happens if I receive back as change a note which I had previously marked? ie I got back one of my own bills? Does this count as a hit? Or do I silently smile to myself and use the bill back out into the world again.

Had this happen recently where I paid for something at PetroCan, and then returned a minute later when I decided to buy some lotto tickets. Got the bill that I had previously used back as change. There had been at least one customer in between.

I don't mind if it doesn't count as a hit. It wasn't intentional -- it surprised me that I had this note back in my hand, as I hadn't even been thinking about the possibility as I did these transactions.