This suggestion is more hardware oriented. Ive noticed in the club that i work at that the 4 or 5 djs that play through the night all have laptops and all use serato, but when they change over, they use a second set of turntables and normal vinyl while unplugging one laptop and plugging in another.

I was thinking that you could create some sort of adapter that could take 2 usb connections that plugs into the serato box and do the required programming on the software side so that when 1 laptop is plugged in, the laptop gets the input from both turntables and when a second laptop is plugged in, either serato decides or the user chooses which laptop gets input from which turntable. Then when the first laptop is unplugged, it goes back to normal.

It may be more worth it just to get 1 extra serato box and maybe the serato box isn't capable of being controlled by 2 laptops through its 1 usb port, but its just a suggestion.