I tend to keep completely separate physical machines. I have Thinkpad provided by work, and a personal Thinkpad. When the workday starts, the work machine goes in the dock, then at the end of the workday, I swap it out for the personal machine.

I'm a strong believer in using company hardware only for work, and never using personal hardware for work related tasks, if only because it makes things slightly less complicated with regard to who owns what IP.

EDIT: Correcting typos.