Well you need only to scan the channel and find all the nicks which have the same address as the one you want to kick, having supposed you have done a /who #chan before hand, you can use this little alias :
Code:
alias kick2 {
  var %chan = $$1
  var %nick = $$2
  var %reason = Clones not allowed
  var %i = 0
  var %MAX = $nick(%chan,0)
  while (%i <= %MAX) {
    var %nick2kick = $nick(%chan,%i)
    if $address(%nick2kick,2) iswm $address(%nick,2) { kick %chan %nick2kick %reason }
    inc %i
  }
}

Hope I have helped you smile