I have mine spread over 2 monitors.. but only slightly. The main render window is maximized to one monitor, and I have the adjustment dials on the other monitor. Kinda nice like that.. :)

http://wonderchef.pridelands.org/Renders/Test/Untitled-1.jpg case in point.. :)

 

Currently using Poser Pro 2012 (Display Units = feet)

AMD Phenom II 3.2ghz (6 cores)

8gb RAM

Windows 10 Pro 64bit