Very hard to tell, have looked at the shadow detail and what there is appears to be matching.
Looking at overlap details show no obvious aberations.
Have to go with it being a real picture.
As Yorkie370 points out when using a long/telephoto lens you get "image distortion" in the form of compression as such an object further away will appear much closer. As such the seperation between the aircraft is greater than what it appears to be.
Oh yes short/wide angle lens have the opposite effect fo this, hence you can use them to give cars long bonnets and models legs that go on forever.
Mike