The two black CD plates are probably 1970s or 1980s as they were both in older collections. Real Qatar CD plates are cast aluminium and have been since the 1960s. The real plates are removed before the vehicles leave the country. If these are genuine plates, they are plates put on in Europe I would guess (they are made on a French machine) as the vehicles would have been plateless otherwise.
The 1997 series 123456 is the only sample I know of from this series and has 66 at the top left. All real plates from this series have 01 as this is the Qatari vehicle class number.
The yellow taxi plate is a rejected test design.
The royal 7812 and 812 are reproductions and nothing like genuine Qatari royal plates.
Two blue police plates: One correct white on blue but it is mint and the number is way too high as they have still not reached 9999 yet. The other should be white on blue not black on blue.
Two green private transport plates: There are actually more of these white on green plates in collections and they should be black on green. There are also quite a few mint black on green plates in collections. Samples for sure but at least they are the correct type.
Two different coloured ‚forced labour‘ plates. The top one is from an Utsch brochure and Qatar never used ‚forced labour‘ plates. It is understood this was a possible prison service plate.
A black and a red QATAR test design probably for heavy machinery and for export vehicles respectively. Both maybe from the Toennjes company in Germany. Not real plates.
UN plates: There are a few UN vehicles in Qatar but not many. They use (and have done since the 60s probably) cast aluminium plates very similar to the CD plates but with UN instead of CD. These samples here are direct from the German factory and nothing like any UN plate that has ever been used in Qatar.