Since Silverjuke 2.10 you can use two monitors in the Kiosk Mode of Silverjuke - eg. one for the Visualization or for the Karaoke screen and the other for the main window.
You have already two monitors? Great! Just open "Settings / Kiosk Mode / Monitors" and define which monitor to use for which purpose:

You do not have a second monitor? No problem: Often there is a second laptop or another computer available - if so, you can use this computer as a second monitor using the software MaxiVista from our partner Bartels Media.