Interesting page with Cottbus stamps.
The cancellation design appears original (I found a similar cancellation in "stampsx")
You must check if the cancellation is not done on a printer.
According to the notation (1 -16x) at the top right of the page, it seems that you have the more valuable stamps (paper type x - you have to check)

2 types of paper were used:
x = white, woodfree paper
w = fiber paper
I only have w-type paper - notice the fibers:

The stamps with face values in Mark in the first issue have the printed background (it can be seen on the white areas of the stamps) and have type w paper.
These 4 stamps in the second issue no longer have the printed background and have type x and w paper.