Update. Changed the wired keyboard for a wireless Logitech 760. The erratic behavior with inadvertent typing seems to be gone.
Alex 3.1 GHz 13" MacBook Pro 2015, 8 GB RAM, OS 10.11.2, Office 2011, TimeWarner Cable 2.8 GHz Xeon Mac Pro 2010, 16 GB RAM, OS 10.11.2, Office 2011, LAN
