1920 Variations Of Germany Official Mi. 33 ?

I got these in a set, but no idea if all three are the a) standard issue (Sienna to blackish-sienna). Other variations are b) peacetime paper and gum (reddish brown) and c) wartime paper and gum (reddish brown).
I don't have experience yet with gum and paper types, but I can see slight color differences.
Took some pics front and back.... anybody see anything unique between them or am I smoking the hopium?

After 35 years of KGVI collecting, I definitely see the different color attributes but don't know enough about these specific stamps to know if have catalog-listed color variations.

Here are a, b and c:



b and c are the same color; b is the peace printing and c is the war printing. The difference is in the way the ink covers the paper. The peace printing shows the ink as smooth and fully covering the inked area. The war printing is somewhat blotchy. The difference is subtle and a magnifier is really required to see it.

Great images.

Germania, thanks a lot for posting the pics.... I'm thinking I just have the regular issue, with the one on end being a slightly different color.