From Reliable way of identifying multiple display —
Some displays, such as @cwilms-loyalist’s Epson projectors, don’t publish a serial number or other unique identifier. If you have multiple of these displays, you get multiple identical entries in Vuo’s Screen input editor, so you can’t predictably select the one you want.
Vuo could work around this by adding a section to the Screen input editor that shows which port on the computer each display is plugged into.