apple 10.9.1 MS office two screens simultaneously working on MS word on one screen and PPT on the other
If you activate "Displays have separate Spaces" in the "Mission Control" Preference Pane in the System Preferences (logout is required), you can use booth screens with an fullscreen applications (CTRL-CMD-F).

I tested this under OS X 10.9.1 with MS Word 2011 v.14.3.8 and MS PowerPoint 2011 v.14.3.8.