This is new! Are they practicing? http://cgi.ebay.ca/100-U-S-20-good-practice-points-voucher-coupon-note-/220629193686?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item335e8653d6
I'm pretty sure these are training notes that the Chinese use for their bank tellers. They use a large variety of foreign notes with these overprints on them. They use these to train their people how to recognize foreign bills, but there are also a large variety fo pure fantasy notes that are often sold as teller training notes too.
Don't know more about these I'm afraid. I've seen images of them and read other posts about them, talked to a few people who've had these with some Hell Banknotes as curiosities. I'd imagine they are very close to the same size, and only color copies of notes with serials blocked out, overprints, etc. People I've talked to said they are not quality paper, but somewhat similar to the Joss Paper used in Hell Notes.
I don't think "Voucher Coupon Note" is a good translation. The Chinese on the U.S. note states: "Training Note" "Banknote Sample" "For training use only, prohibited from circulating" The Chinese on the French note states: "Banknote Sample" "Training Note" Gary