Is it possible to run two postdocs simultaneously if one of them is "independent"?
It is hard to predict what is &quot;possible&quot;. Your contract(s) and policies may stipulate expectations.
But to be safe, I would suggest, only do this with everyone's knowledge and permission. I doubt that it would be given, I guess, but you could suffer if you do it &quot;on the sly&quot;. If you do a good job in both and no one learns of the deception then you might be ok, but that certainly isn't assured. And, working it out in advance will help make expectations clear and avoid any legal issues.
Also, it is good to sleep, occasionally and to have an actual life.