In December 2015 these plates were being offered by Ebay seller amirenduro2013 from Sarajevo in Bosnia and Herzgovina. You can see where these mint plates have been wired onto a display board presumably in the police plate issuing office in Sarajevo. They are very similar to the plates that together5882 was selling and have probably come from the same place.
The Tunisian plate is a 1990s test design that was never adopted in Tunisia.
The Dubai plate and the OSCE plate are samples.
The UNMO plate, that he says is UN Military Observers, is a fantasy design and the UN have never used the letters UNMO on any plates.
These are all manufacturer’s samples and rejected test designs given to the police when the salesman was trying to interest them in buying from his company.
If you buy mint plates like these, you will end up with rubbish in your collection.