As I try to write this article, my friend and I have six different screens attached to three types of devices. We’re working in the same room but on our own projects—separate yet together, a comfortable companionship.I had never really thought of the proliferation of screens as a peacekeeping tool until I stumbled across one of Allen B. DuMont’s 1950s dual-screen television sets. DuMont’s idea was to let two people in the same room watch different programs. It reminded me of my early childhood a...