In the 'German Tanks' section, topic 'Loading Beute' there was some mentioning of German use of Traction Engines. I found this website, dealing with the Kemna EM (Einheitsmaschine). Thought it might interest you.
The engine in the photo of the beute recovery process could perhaps be a Kemna - this would explain both the Fowler like similarities and the differences (such as the cylinders). However the Kemna in the article is a road machine and I still wonder why a ploughing machine was being used to recover tanks, unless it was an impressed machine.