[xAndrewx]

function onPlayerChats()
{
  curBiz.loadVars("levels/archtype/businesses/business_" @ this.bizName @ ".arc"); 
  temp.playerChat = player.chat.tokenize();      
  switch(temp.playerChat[0].lower())
  {
    case ":addmember":
      temp.curPlayer = findPlayer(temp.playerChat[1]);
      if (temp.curPlayer == "")
      {
        return false;
      }
      if (curBiz.curMembers.index(temp.curPlayer) >= 0)
      {
        return false; 
      }
      curBiz.curMembers.add(temp.curPlayer);
    break;
           
    default: 
      temp.notSave = true; 
    break;
  }
  if (temp.notSave)
  {
    return false;
  }
  curBiz.saveVars("levels/archtype/businesses/business_" @ this.bizName @ ".arc", 0);  
  chat = curBiz.curMembers;
}

I removed a few things, as most isn't necessary for what is wrong.
Basically, it shouldn't be able to add a member that is already a member. Apparantly, 'if (curBiz.curMembers.index(temp.curPlayer) >= 0)' doesn't seem to be working. Anyone have any clues?