It looks like your MA props are plastic and the TF is wood. I think difference in rotating mass could cause this. The speed of the crankshaft is not constant. It slows under compression and accelerates after ignition. How that interacts with the flywheel action of the props could cause a problem like this. It should be noticeable as torsional vibration. Another possibility is that although the prop was statically balanced on a balancer, dynamic balance was out. This shouldn't be a huge problem because props are short in the axial direction. One last idea is that one blade has significantly more pitch than the other.