For comps, you cut the MM away from the butt, so that it just hangs on by a small area along the bottom (fat cap side). Then, you cook the butt as a "whole" piece. It takes great skill (which I don't possess) to get the MM to finish at the same time, but at a different temp than the rest of the butt. Most of the time, I end up under-cooking the butt for the sake of the MM, or else I cook two butts, one for the MM and the other for pulling.
President & CEO, Oakridge BBQ LLC
~ Visit Oakridge BBQ ~
Oaklahoma Joe 20x40
26½" Weber Kettle