Thank you "floortrader" for the idea of using French occupation stamps as a reference for war printing ; unfortunately the 50 pf stamp was not used.
Another identifying of the war print is the subsequent obliteration of the month of March/April 1915.
Whoever owns a large batch of 50 pf stamps (not my case) can observe the characteristics mentioned in Michel: Print peace – Clear, clean print, cleanly defined lines, silky, shiny colors ; Satin-finished, glossy paper ; watermark clearly recognizable ; white gum, matt glossy, finely brushed.
War Print – Blurred, unclear print image, drawing often interrupted, dull colors (very glossy in the first roller prints) ; dull,rough paper ; Wz.unclear, not always recognizable ; Gum glossy to high gloss.
I noticed that on your "peace/war" stamps the center is black.
The stamp on the left posted by "Mainer" has a brown-black center on a brown-orange mat different from the one on the right which is black.
Hence my hypothesis that it is Mi 76 issued in 1902 on paper without watermark.
On the stamp on the right (at the resolution of the post) I did not notice the characteristics of the war print (but that depends on experience - which is not the case for me)
I found on another site (at a better resolution) a printed war stamp:
