It's something that every massage enthusiast should try at least once.
If you go the semi legit route, it's just a great feeling having four hands massage and relax you throughout the entire session. The finish may be great or ordinary, depending on how well the two MPAs know each other and how they work together.
If you go the body rub (Muse, Premier, etc.) route, you're best to ask one of your favourites who she likes to do duos with. If you get two MPAs who are into each other and are willing to play and share, it can be an outstanding ride.
If you get two MPAs who are just thrown together, there's a risk that they both hold back on their usual mileage and your session could be a bit of a bust.