I'm not a techy, but many scanners/copiers have built in technology that prevent the scanning and copying of currency.

at my work, we have two high end color copiers and neither one will copy or scan paper currency. they wouldn't scan american bills (we tried a 20 and a 100) and I happened to have a $100 RMB (china) note from a recent trip in my wallet and it wouldn't scan that either. the chinese note is different in size and color than an american note so somehow the software in the scanner knew.

I don't know how it works and I don't know if all scanners/copiers have this. I haven't tried it on my cheap @ss scanner at home though. I may do it just to check.