Theres 2 main ways that our group do Duos.
Tag Sets : This works with whatever equipment that you guys are used to…I have done quite a few tag matches and it just works that you guys do like a mix or 3 or 4 songs and just switch off…This is a lot of fun cuz you always try to top each other to keep the energy level really high and bang shit out till you close the night down. I will use my S4 and my friend will be on the CDJs i do my mix on CH1 and when im done he will use the other 3 channels.
DJ Duo : This is more for like a big room setting (+300 ppls) We will have my friend or myself mixing and will have the other person on my effects controller, dealing with punters who come up and hyping up the crowd, either dancing fist pumping whatever it takes, and then we will switch off and vice versa. This setup requires that you have 1 guy doing all the mixing and the other guy having a separate effects pad or another midi controller (RMX-1000/Midi Fighter/Kaoss Pad etc.)
2 most Effective ways of using more than 1 person behind the DJ Booth.