Some blades are cheap steel, and, have teeth that are softer or harder, so, setting 2 teeth at once might not be a good idea. How will you know if a tooth is not set near correctly ??
I made a dual tooth setter, and, only used it a few times, because of this. I have set a bunch of blades, using the single tooth WM setter. I will see if I still have photos of what I made. It was copied from the TimberWolf design, I believe it was, out of New York City.