Hi DeFrag. A lot of the old Gretch guitars had kill switches and the Phase one Univox HiFliers had two rocker switches to control the pickups until 1971, that allowed you to kill both pickups. I don't know who had the first one. Good question for the historians here.
I didn't know about them when I installed mine! Hell, I was so new.. I didn't even know about the Gibson LP volume down pickup selector trick back then.