[thfuran]

But 2 PSUs plugged into the same AC supply still have a single point of failure.

[glitchcrab]

Which is why you have two separate PDUs in the rack which are fed by different power feeds and you connect the server's 2 PSUs to opposing PDUs.

[growse]

This works brilliantly, right up to the point where your A side fails, and every single server suddenly doubles their demand on B.

Better have good capacity management so you don't go over 100% on B when that happens! (I've seen it happen and take a DC out).