In my opinion, the overall cost of a watch winder is contributed by the housing, motor, R&D, and any A&P involved in marketing the product; not forgeting overheads.

So, some companies try to reduce this cost by making one motor (rotor) to rotate two watches on a single winding turntable. Another way they could achieve some cost reduction is by using gears and belt-drives to rotate two turntables simultaneously.

Scatola is one good example where they deploy individual rotors for individual watches. This is an expensive way but a good solution for proper watch winding and pampering.

When buying watch winders using two motors, each individual watch will get its required winding direction including the appropriate TPD and users may even choose to select the TPD and Direction individually. Each motor will have its own driver circuit, thus increasing cost.

Using a single rotor to wind two watches will give one watch the required TPD but the other watch a lower or higher TPD. There has to be a compromise between cost and functions. Since we know that watches require a certain minimum turns to keep wound, setting it with a little higher TPD, say between 800~1200, would be alright.

Most high-end watch winders uses the one-rotor-one-watch winding method while the affordable ones just winds two watches on a turntable.

I'm in favour for individual winding heads among the two systems. Although it'll cost a little more, it's worth the money spent.