Some interesting analysis made in this translated article:
664/5000
to download for the inventory of wrong signatures, there are today the following pictures with the wrong signature OECHSNER BPP.
The signature is located on a DR 112a. The "b" can also be distinguished from the black-and-white image. The "b" shows an extremely porous print with many white spots, in particular also in the lower region of the mark. Note the spots (at 112a not available) above the word flight mail. Following pictures of real 112b (these canceled stamps are rarities, with the kind permission of the auction house Felzmann, Düsseldorf show) and the real signature OECHSNER BPP and the dubious pieces.
112a with wrong signature:


Real Signature:

Mr. Oechsner always cuts his test post accurately. Fold marks are not signed deeply.
Real 112b:


From stamps X forum(original).
http://www.stampsx.com/forum/archiv...ic.php?id=66