the appearance/location of your clone is determined by messages coming from the server to your main's client. same as if the clone were actually a person on another computer on your LAN. basically, your clone will perform an action (like move ahead 3 steps)... that is sent to the server then sent to nearby characters so that they may display the action. if the action does not appear, that would mean the packet describing the action was lost somehow (or at the very least, not processed for some reason)

definitely sounds like latency, packetloss, or something wrong with wow's protocol.

what OS are you using? network card? how many clones per machine? what are your system's specs? (low-end cpu could get overloaded easily... increasing packet loss)