I found a post elsewhere that helped.  I am new to dual display so couple questions.  The technique I found extends the display.  I can't get two Excels onto two separate screens; just on one or the other.  Any help on getting two Excels onto separate screens for simultaneous viewing?

The tecnique from another post is: "It's not that complicated. Simply plug in an external monitor, boot up, go to the display properties -> Settings. Then there should be two monitors displayed there. Click on the "2" and then click the tab that says, "Extend my desktop with this monitor". Click "Apply" and that's it. "

I had to work out second display resolution issues with "plug and play m onito" selection vs "default".

In control panel display properties settings where the icons for the two displays are has more significance than just right or left position of monitor 1 and 2.  You need to drag the two to touch and be level  as well as same size, then the Excels become proportional even though screen sizes may be physically different on actual monitors.