Is your server license enabled for clustering? If not, then the QV Server services will be on stand-by until you stop the other QV Server services. This depends on the version you have, but since QV 9 you should be able to see the other QV Server in the QV Enterprise Management Console in Status->Services and then selecting the QV Server service. You should see an error that says that the service is not able to do a cluster with SERVERNAME.
We're currently using QV 9 SR7 and our server license is not enabled for clustering. I don't see the name of the other servers in the network that used the same license in the error message - only the message Cluster Count Exceeded. It be great if I can identify the specific machine so we can clean them up (i.e. remove Qlikview from it and consolidate, etc).
It seems I was a little off. QV telling you which other QV Server exists by server name must have been new in v10. You might be able to find software that scans the ports or services of other computers to see which computer is listening on the port 4747. Otherwise, it might be easier to temporarily install v10 and have QV tell you which other computers have QV Server.
I gave the power tools a try with QV9, but it can only detect the localhost server, not the other QV servers on the network. We're in the process of upgrading to QV11 and the power tools are working there. So I guess it's way more useful to be in QV11 (or at least QV10) to know which servers are using the same license.