6x4.5 back question

I've been thinking about acquiring a 6x4.5 back for my RB kit. I've not seen any with the double exposure switch or the Pro S badge.
Did Mamiya ever produce one or must I trust my ancient memory to remember to wind on between frames and not to pull the dark slide when the back is removed or remove the back from the body without replacing the dark slide etc?
Seems to make this format a bit less attractive as I'd probably screw up enough to negate the advantage of having more exposures. lol!

Larry

Answered my own question. There's a brand new in box Pro S on the bay right now (with the finder mask even!). Kinda pricey but it's the only one I've ever seen in a few years of looking. Guess I'd better grab it while I can.

Good brand