Cannot enter a bill that I entered before

I just had a $20 bill come back to me and I found this out because I could not re-enter it. It would be interesting to find out how long it was out of my hands before I got it back.

You should be able to check your history of entered bills to see when you last entered it.
It has happened to other people before, (getting a previosly entered bill back) and you dont get to enter it again.
I believe this is to discourage cheating.

Mike Cityscape

When it tells you that you have already entered the note,you can click on the serial number and see when you entered it…