I still don't understand why the OP discounts the question "Why?"
Why is this photo in question but not others? There are apparently 57 dry plate negatives from the Wright Brothers cataloged at the Library of Congress. Many of them show an airplane in the air? Are all of them in question or just this one? And if so, I ask again, why this one?
Perhaps Designer's right - there might just be some beer and a couple of ill-advised bets behind this
Well there are a couple of different conspiracy theories floating around on that one I guess, first that the Wright brothers were not the first to acheive powered flight. Some folks want to believe that a guy named Gustav Whitehead was actually the first and that the Wright Brothers stole a lot of their design from him - I haven't found a ton of supporting evidence there, while I have little doubt that Whitehead probably was working on designs for powered flight there just isn't much historical evidence that he acheived it first or that he and the Wright brothers actually met at all.
The second one I've heard is that the Wright brothers supposedly faked everything prior to 1908, but that makes pretty much no sense to me whatsoever. They supposedly spent 4 years pretending to have a working flying machine and went to huge lengths to con people into believeing it worked, then in late 1907 early 1908 they submit a proposal to the government for a contract and they plunk down a $2500 deposit knowing full well that the government is going to demand that they prove this works or they lose the $2500 deposit. They do this supposedly knowing full well the machine doesn't work and that they've been conning people for the last 4 years.
Then suddently in 1908 they magically pull a working model out of their keesters that drastically exceeds all of the performance expectations at the time and they manage to prove to the government it does work with multiple public demonstrations in front of eye witnesses, many of which are caught on film proving the design works. Just makes pretty much zero sense.