I had a same problem, Ii need to use two windows of one browser, I need check the list of browser compatibles with MouseMux

It should work fine! (just tested it myself). Open two chrome windows, select multiplex mode and click mouse A on window 1 and mouse B on window 2. Now you can click/work simultaneous in the windows and browse independently. For the keyboards to work make sure you pair them with the mouse (see the keyboard tab for that).