I have a desktop computer with onboard VGA and option to add a
discrete video card. It has plenty of spare USB ports for mice and
keyboards.
Does Debian support using this computer for _two_ workstations, each

with their own user accounts, monitor, and keyboard?

Also, I thought Kent West was doing this as well, but I could be
wrong.

I was interested in doing it, but never pursued it to completion. I'm
confident it can be done, but that's based on a gut-instinct rather than
actual knowledge.