Bit of a strange on this. I have pulled of 2 rolls of 120 out of my Bronie, the first one had a few dust marks, nothing unusual about that, but then the seconde film a week later had the same marks in the near on the same places as the first.
It was a memory thing at first so checked. They were the same marks. The marks were on the prints in the same position, with a bit of give a take, one here and not there. Under inspection the lens in side the camera had bits of dust on it. Bit of bad luck or would these little bits really be put into play under the enlarger light.