I just want to know if playing with a friend in the same room is against the rules, because some people call this dual-clienting . But in my opinion it's not, it's what i call a LAN .
So i just wanted to know if i can be banned for playing with my friend with 2 different PCs and the same IP.
Dual-clienting is considered You (as a single person) playing on 2 computers, with 2 characters. As you are going to be 2 individuals playing in the same room it is not a dual client.
But yes dual clienting is one person playing multiple accounts at one time.
Playing with your friends in the same room is not only legal, and fun, but strongly recomended because then when they mess up and cause a party wipe there are real world consequences.