Mine

on !*:Join:#Trues: { 
  if ($ialchan(*!*@ $+ $gettok($address,2,64),#,0) > 1) { msg # Clones detected. :: ( $+ *!*@ $+ $gettok($address,2,64) $+ ) :: $chr(91) $+ $ialchan(*!*@ $+ $gettok($address,2,64),#,0) $+ $chr(93) :: $cn(#,*!*@ $+ $gettok($address,2,64)) }
}
alias cn {
  var %x 1, %temp
  while ($ialchan($2,$1,%x)) { var %temp = %temp $ialchan($2,$1,%x).nick | inc %x }
  return %temp
}