KVM switch I have one on my deck right now, hit a button and my monitor, keyboard and mouse are all connected to a different computor. One could be on the secure net and the other could be on the internet. One possible solution out of many possible solutions to the problem you offer.
So, double the IT workload, and remove the ability to cut/paste from one datasheet to another?
Just means that there will be more intensive firewalls - we are almost secure to the point of non-functionality where I work.