With some focusers, when you purchase them you can sometimes choose a model which has a different USB id.

Like here for instance: www.firstlightoptics.com/astronomy-cable...ocus-controller.html

Note that there is the option at purchase to either buy "HitecAstro DC Focuser" or "Additional HitecAstro DC Focuser".

Quoting:
Existing Owners - Multiple Controllers
For existing Hitec DC Focus owners who wish to add a second controller to use alongside their existing one please select the 'Additional' option above.

This allows you to run a second controller in parallel with the existing controller on the same PC. In every other respect HitecDCFocus2 is exactly the same as the original.

Running two of exactly the same device from the same PC is not normally possible as the USB identifier would conflict and the PC would not know which one to talk to. HitecDCFocus2 contains a separate USB identifier so that they can be run side by side.

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