What ?

Today (Wednesday) was the second day with full sunshine.   There are a lot of military aircraft that fly the skies over the Florida Panhandle. I was down on the beach set up for bird photography when this big prop plane flew over.  It was a 4 engine prop plane.  I am not very well versed on military aircraft so I cant say anymore about it.  This image was captured at a shutter speed of 1/1250 sec.  Fast enough to freeze the motion of the plane and even pretty much stop the rotation of the 4 props.
But..if you look closely at the props there is what appears to be ghosting in a spiral pattern of the prop blades.  I haven't yet wrapped my mind around what is going on here.  Everything is reasonable sharp, but yet the props show ghosting???