Credit: http://tips.timscomputer.com/disable-powerpoint-2013-extended-display-mode-via-registry/
Disable the extended display mode upon login, same as the link just modified the version from 15 to 16

Run the following as a batch file upon login

@echo off
reg add HKCU\Software\Microsoft\Office\16.0\PowerPoint\Options /v UseMonMgr /t REG_DWORD /d 0 /f