Regarding the US $50 bill practice note. I have not seen this before. It may be just a flea market item, but many different kinds of practice notes are used in China. I have perhaps 20 different kinds in my collection, but they are all in Chinese, naming various Chinese banks, or no bank at all. It is possible a set of imitations of US notes are being used to train tellers who will handle U.S. currency. I hope they are aware that both old and new types of note are in circulation. The imitation note is very close to the real thing, but it lacks serial numbers.

By the way, also yesterday I received an email from a guy in Indonesia who wants to sell his U.S. $100,000 bill. He sent and image of both sides, and it does look like the genuine note, though the image is too poor to make any judgement. However, the note is heavily worn. These notes were only used to make transfers between Federal Reserve Banks, and as far as I know, all of them are accounted for. There should never have been any in circulation or private hands, and they certainly would not be heavily worn.

This is the first time I have seen a Chinese teller training note with a proper back. Most have the back covered by the name "Bank of China" repeating in a dense lattice in English and Chinese. Even when single faced, being life-sized, they are illegal, and double faced they are illegal regardless of size.

I showed that image of a Chinese "practice note" to one of my Chinese students. She translates the characters thus:

Training Money
SAMPLE
Only for Practice – Circulation Forbidden

Apparently (as my student tells me) the characters for "Training" are also those for "Kung Fu", so perhaps "Kung Fu Money" is another plausible rendering.