It will probably be easiest (and less warranty-voiding) to solder up a Y connector for both the the positive output and the negative output. Not sure what sort of output plug is on the power supply, but I will assume it is a female banana jack. You need to make the Y for each one with a male plug on one side and 2 female plugs on the other, then heat shrink it to keep it safe. I suppose if you want it to all be enclosed in the PSU's case, you could drill 2 more holes next to the current jacks, then install the new jack in the holes, wiring it is mentioned above. Keep in mind that if it's a 23A PSU and you're using 2 chargers or whatever at the same time, they will each be able to draw a max of 12.5A. Hope this helps