I was actually just wondering this too.
This may be silly, but I actually had a dream the other night where i was in this little craft boutique. There was a display of these homemade soaps. They were CP soap that had really cool designs carved into them - pirate ships, animals, native american designs, etc. Then there was a thin layer of clear M&P soap on top of the carving to act as a protectant of the intricate carvings.
Is something like that even possible? Is layering the two types possible at all? I've never even done M&P before - i've only worked with CP.