"Duplicate these displays" doesn't work in Win8 guest

[pufferdude]

I'm running Parallels 8 on a 15" MBP and have a Win8 guest set to "Use All Displays in Full Screen" so that Windows can see both monitors. I am trying to set it up for a presentation where I want my Win8 desktop DUPLICATED on the external monitor, but when I go to the display settings in Win8 and choose "Duplicate these displays" it instantly changes my selection to "Show Desktop Only on 1" and asks me to apply. Similarly, if I do Windows-P to change presentation settings and select "Duplicate" it does nothing.

It appears that there's no way to get a Win8 guest to duplicate the desktop across two monitors. Is this accurate and just a limitation of Parallels, or am I missing something?

 

[pufferdude]

Ok, after further testing it looks like the Parallels guest must "follow" whatever monitor setting the host Mac is using. If OSX is set to "extend display", then the guest VM can ONLY extend its display. If OSX is set to mirror displays, THEN the guest VM can mirror (must, actually) its display as well.

This is unfortunate and I'm not sure if it's a hardware limitation or a deficiency in Parallels. Does anyone know if Vmware Fusion behaves the same way in regards to dual monitors?