This might be one of those reasons why I'm not an electritian, but is it dangerous.
Back when I worked at a high-availability data center, all of our servers had dual psus, plugged into seperate circuits.
The transformer in the PSUs should electrical isolate the mains voltage from the low voltage side, so you aren't going to cause a short across the two circuts.
The only risk I see is a cascade failure, where the increased load on the second circuit causes its breaker to trip.
Back when I worked at a high-availability data center, all of our servers had dual psus, plugged into seperate circuits.
The transformer in the PSUs should electrical isolate the mains voltage from the low voltage side, so you aren't going to cause a short across the two circuts.
The only risk I see is a cascade failure, where the increased load on the second circuit causes its breaker to trip.