No. They are (or were when I was part of MM) the exact same pot. The mastering version simply used a version of that pot with a detented section added.
But as I said, that was then. I have nothing to do with MM and have no contact or communication with them at all, so I have no idea what they are now doing with the products. Therefore, as always, YMMV.
I can take a stock unit and make is a mastering unit because I have the detented sections for the pots. I often do this with EQs that I've added my new main PCB to. Most of the people buying the new pcb are mastering people and they want the stepped controls for mid-band freq and Q. Mastering people also typically want the vastly improved sonic quality, selectable boost/cut gains, and elimination of the tube section that the my pcb offers.
I hope this helps to answer some of your questions.
Thanks,
Fred Forssell