Something

on *:text:!dm *:#: {
  if (%dm. [ $+ [ $chan ] ] == on) {
    if (%dueller1 == $null) {
      set %dueller1 $nick
      msg $chan 10 $+ $nick 3 wants to duel someone, type !dm to accept the duel!!
    }
    else {
      set %dueller2 $nick
      msg $chan 10 $+ $nick 3accepts the duelmatch!! 
      set %first $rand(1,2)
      if (%first == 1) { 
        set %attacker %user1
        msg $chan 10 $+ %user1 3Strikes first!!
        if (%first == 2) { 
          set %attacker %user2
          msg $chan 10 $+ %user2 3Strikes first!!

        }
      }
    }
  }
}