"Duplicate Name Exists" Errors in Windows
After starting up a Microsoft Windows computer connected to a local network, you may see the error message "Duplicate name exists." What does this error message signify, and how can you resolve it?
The "Duplicate name exists" error indicates the (NetBIOS) name of the Windows computer conflicts with some other name on the network. Most commonly, this happens when another Windows computer on the local network uses the same name. This error can also occur when one of the connected Windows workgroups has the same name as the computer.
"Duplicate name exists" errors prevent a Windows computer from joining the network. The computer will start up and function in an offline mode only. To resolve this error, simply change the name of the computer to one that is not used by other local computers (or Windows workgroups), then reboot.
Note that a network administrator should also verify the Windows Internet Naming Service (WINS) is up to date.