I cannot use Firefox for VMK for some reason, so I am in IE.
I went to the sign on screen and then saved the link as a shortcut to my
desktop. Then I'd sign in to the screen already up.
In order to open a second sign on window, I'd click once to highlight the
shortcut icon. Then I'd hold down the Shift key and then double click the icon .
By doing that, you override the window, and it will open a new window.
You should be able to sign on your second character from there.