Many Redundant Power Supplies use the shared load principle.
For instance with a 460W 2+1 Redundant Power Supply which consists of three x 230W power modules, two out of the three units provide 460W together, when one module fails, the third one takes over.
When it is possible to replace a defective module while running (without shutting down the server/workstation), it is called hot-swap.
A redundant power supply delivers better uptime by making sure a server/workstation doesn't go down when a single power module failure occurs.