According to this site:
http://www.joebaugher.com/usaf_serials/1943_1.html is the plane with serial number 43-4450 a B-25H-5, not an A model. The engines are pretty much the same on the A and H-models, R2600-9 on the A model and R2600-13 on the H model, both rated at 1700 Hp. So they should have the same 3-bladed propeller.
B-25H-5 serial no 4406 was modified as NA-98X with R2800 engines. First flight Mar 31, 1944. Maybe it got 4-bladed propellers? And maybe the same thing happened to this plane? Just a thought.
Skarphol