Hello,
I was thinking about this. So what if you were to make a copy of your wallet with 10 BTC in it and save it to a USB. Then you send 1 BTC to someone else's wallet. The copy of your wallet shows it as having 10BTC so if you were to put it on another computer and use it as the wallet.dat file, wouldn't that account still have 10 BTC even though you just sent 1 BTC to someone so if you did this in between three computers, you could generate free BTC?