Query: why a 4-pin DIN plug on a 5 VDC 10 A supply?
Power supplies with elevated output (10 A and more) need adequate connectors to deliver the current. They usually came in different variants, including so-called "power 4-pin DIN" connector:



The contact rating is 7.5A per pin. Therefore, to handle 10 A they use two pins and two wires. They usually are used in parallel at the destination board, or could be used separately, provided that contact rating per pin is not exceeded.

P.S. There might be more sophisticated schema for power delivery using four-wire Kelvin connection, to get voltage feedback from the actual point of load and compensate for voltage drop along the leads, but this doesn't sound like the case.