JLC Reverso Case Finishing

Only on the Duo Faces. Traditionally they had 1 face.

As you say the split dial is likely only for the Duo models. I believe it is done so the watchmaker can access the balance from both sides of the head for hand synchronisation or perhaps regulation. Makes sense if you think about it.

The dial on reverse is a virtually useless complication really (and removes the Reverso USP of being tough enough to play polo) but when I saw it for the first time I knew I had to own one. It seemed like magic, the main hands of course can't be directly connected since they rotate in opposite directions. It is an elegant answer to a question no one ever really asked!

I have this shot too, also taken on the Richemont workbench by a pal showing how small and delicate the Duo movement actually is. All the more remarkable considering it has a 24 hour complication on the reverse side to the second hand:

Not sure I'd agree about that... I use mine as a dual time zone watch when travelling on business. Minimum of fuss to flip the case at each end of the flight & much smarter than the GMT diver style I use on holiday by the pool. Of course, it's lovely in daily use too - but it does have some practicality too 😉

Yup. My Duo and my GMT Master 2 were my travel watches when I was living out of a suitcase. Second face is both home time and another look for the watch.