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A duplicate name existing on the network happens when two resources - usually computers - have been given the same name. We'll look at how to check, and where to fix it.

Windows System Error: A duplicate name exists on the network. I get this message in a little nag box when I sign on. It doesn't come up every time, so has someone hacked in to my computer?

It's unlikely that you've been hacked.

It's more likely that the error message is exactly right: A duplicate name exists on the network. The question you're probably asking is, "what name?".

Your computer's name.

Right click on My Computer and click on Properties. Then click on the Computer Name tab and you'll see something like this:

System Properties - Computer Name dialog

Yours will of course have different computer descriptions, names and Workgroup names.

The error message is complaining about the Full computer name listed there. Each computer on your network must have a unique name. If two computers have the same name "a duplicate name exists". In such a case, some network operations may fail because there's no way to tell which computer you mean when you specify the computer name.

Computer names should also be different than the Workgroup name.

Pick one of the two computers that have the same name, and pick a new name.

To change the name, on that Computer Name dialog, just hit the Change button, and you'll see a dialog such as this:

System Properties - Computer Name change dialog

As you can see, you can change your computer name to whatever you like, or change the Workgroup it's a part of. (You probably want all the computers on your network to be a part of the same Workgroup to enable file sharing more easily.) Once you change the computer name, OK your way back out. Reboot and see if the error message you were seeing hasn't disappeared.

Article C2801 - October 4, 2006

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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Recent Comments
17 Comments

my pc is on a local network and when i change the computer name as suggested it then asks me for a logon to our local file server (i have to point out that we have a very ancient lan operating on NT) once i enter the admin login details, it get another error teling me that the domain does not exist or could not be contacted. HELP!

Posted by: Anthony at July 8, 2010 3:17 AM

Thank you
It was so helpful

Posted by: eyara at July 17, 2010 2:01 PM

thank you very much
It was helpful to sort out the trouble

Posted by: hems at August 14, 2010 3:12 AM

hi..., i have 2 pc desktop, but they are istalled by northon ghost (cloning). connetted but can't ping for each other
how to troubleshoot them..? thank's

Connected how? Are you sure that they're connected to the network? Typically when this happens one or both of them are not, or the router to which they should be connected isn't working properly.
Leo
28-Dec-2011
Posted by: aram at December 28, 2011 9:22 PM

Using your advice I double-checked to insure that my two computers (1 XP and 1 Windows 7) had unique computer names. They were already unique. Also both computers were part of a workgroup. However, the workgroup had the same name as my wireless router network, which is where the "duplicate name" conflict occurred. I changed the workgroup name, which fixed the "duplicate name" error message. Thanks for your help.

Posted by: JimS at February 4, 2012 10:22 PM
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