North Korean Banknotes

I visited the DMZ and got this banknote set (it also had 4 100 won coins for some reason) that had every denomination of banknotes (besides those worth less than one won). The person at the shop said they got it from china.

I found that there is something strange in there (at least something undocumented on this site). The one won banknote has “COPY” on it:

Is this something undocumented or have I not searched enough?

Also what would be it's value?

Corrections and clarifications: 

The set doesn't include a 100 won note :(

The back appears to be normal to me at least

The bill is in circulated condition  

Uncirculated oops

Generally anything with the word Copy on it means it’s a reproduction. I’m pretty sure others will agree with this. 

Here is a “Roman Coin” I just found in a coin lot as an example. 

I do not have the answer here, but from my observation, the note looks legit to me. Perhaps a better image would help us. The one won, presumably P39 1992 print is a cheap note, and for that reason, why would they stamped the word copy on it?

The folder cover seems to have Hanja or Chinese characters writing on it, above the Hangul. Why? The north stop using them in 1949, and the south banned then in 1970, but I am aware that many still can read Hanja in South Korea.

The south has not banned hanja…at least one daily newspaper uses it extensivel...everyone's name is translated into hanja for legal purposes…and as late as 1998 university students were expected to practice and have a working knowledge of several thousand hanja…

Oklahoman is correct, Hanja is still used for many important things such as the traditional burial service. Here are better pictures:

I find it odd that there is are no copy marks on the other notes. My personal theory about this banknote set is that it is made by the North Korean government for Chinese tourists, even though there isn't much Chinese on it. No South Korean manufacturer would produce something with those portraits of the Kim family. Some Chinese person then brought them and sold them to the dealer (they were in the DMZ forgot to mention that) and sold them to me (they were way overpriced I think). Despite other North Korean made things like books and music being illegal to sell in South Korea (such as Kim Il Sung's memoir) and the obvious propaganda portraits on the notes themselves, numismatic items (well maybe not medals idk) and stamps are not illegal to distribute or sell in South Korea. I visited some coin shops in Seoul and multiple of them had North Korean coins or banknotes.