Some quick workarounds are:
* Use the Remote Only setting in the Network control panel, this is exactly one of the situations it was designed to handle.
* Turn off FileSharing at the ARA client.
* Advertise the names of the servers on the ARA Server's zone and tell people not to use them as their personal server names.
NOTE: If you were to try to bring up a personal server with the same name as an existing one while already connected to the network you are told the name is in use and to select another. You will get the same error if you attempt to change the name of an existing FileSharing server to that of an existing server. This is not an ARA limitation, it just gets more complicated with ARA since both servers are already up when the ARA client joins the network.