quick at psu to cd32 question

[nahoo7]

hi i have a y cable connector for at psu and the 4 pin din for the cd32 looking at the previous threads i cant quite see the connections properly concerning the wiring.
I know you connect the +12v yellow and the +5v red and black for ground.
As there are 2 black wires do you join these together or just use one of them cheers

[nahoo7]

thank you very much for your reply just wanted to double check cheers.