Adding to list in RPC

Why will the following RPC function always replace instead of add objects to the list? Both server and client will have the same listOfPlayers with the Count of 1.

[RPC]
private void CreatePlayerSlot()
{
    NetworkUser tempPlayer = new NetworkUser(); 		// create player
    tempPlayer.netID = Guid.NewGuid();		// unique identifier
    tempPlayer.ready = false;				// player is ready or not
    tempPlayer.active = false;				// occupied or not

     listOfPlayers.Add(tempPlayer);
}

I call this one everytime a player creates or joins a game.

void OnPlayerConnected(NetworkPlayer player) {
networkView.RPC(“CreatePlayerSlot”, RPCMode.AllBuffered);
}