monitor/ mirror imaging

and do not choose to extend the deskop

That'll do it.

Avoid any temptation to extend the desktop.

You need to set the Second Monitor to Clone the Primary Monitor or you can use a Video Splitter to split the Video Feed from the Primary Video Out put.

The Splitters can range from a simple one in and two out lead to a Powered Device to split the Video Feed it all depends on the Hardware involved.

Col