Hi Peter
I doubt very much you will find any new force landings in Holland during WW 1. They were all very well documented by (most likely) Dutch Air Force staff. No it is one and the same aircraft labeled as D.5584 in Dutch files, but showing D.5288 on the rudder.
I am also pretty certain that to be able to dismantle aircraft and later make them airworthy for said Air Force, they needed experts.
Of course these experts were familiar with the aircraft models at the time. Especially so a type already in its lifetime at the front considered to be the best fighter around (or at least one of them) and on top "designed" by a Dutchman. So, yes, they knew perfectly well what a Fokker D.VII was.
You say that Clint introduce the name Baum into this context, but he does not! It is actually you who state the pictured aircraft was flown by this mysterious Baum guy. Check your post 1. From where did you get it?
Enhancing photo 39 was very interesting since all I can read is that the strut in question actually says D.VII (not D.7 as written on the rudder). As far as I am concerned it rather "proves" my point (if not the case) that the rudder is a replacement or the scribbles have been made after landing. Unfortunately I cannot read the actual serial number. It could be anything.
Being completely non-technical, I can only assume that parts made to the Fokker D.VII could be fitted to any Fokker D.VII at the time, ie they were interchangable. Having looked at (by now) some photos which shows parts to be either stencilled or painted with both type and serial number, I am not so sure anymore. Why go to so much trouble labeling parts if they anyway were interchangable? At least I need someone with a lot more insight into why this was so, and also how the D.VII production lines were made up.
I am not saying this aircraft is not D.5288, but since all official documents state D.5584 someone at that time either made a boo-boo or knew something we don't....
Cheers
Stig