In the specialized Michel catalog there are 2 varieties with high values #;(see arrows).

The 17000 E variant is excluded (B=roulette)
These stamps (Michel 309) were overprinted with 2Mil. on 200 Mark stamps reissued and with different colors than the original issue (the stamp on the top left).
The cancellation can be evaluated (RAGEBERG) and the date corresponds to the correct rate for cover over 20 gr. abroad.
You need to check that it is flat print (2.5mm distance)
It must be color "c" and this can only be established by expertise/certification.
I have posted a few stamps from my collection (in case you do not have a Michel catalog) to differentiate the differences in printing and perforation.

The color differences are difficult to evaluate.