What Are MixConsole 2 and MixConsole 3?

Why does the DEVICES menu list a MixConsole, MixConsole 2 and MixConsole 3 when clicking on any one of them seems to bring you to the same single MixConsole?

They can be configured differently,
For example use mixconsole 1 to show all, mixconsole 2 to just show inputs, mixconsole 3 to just show outputs.

Are they only different views of the same thing, or are they actually independent mix consoles?

No, you can link all 3 mix consoles if you wish. Here is my basic set up with 4 monitors.