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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.

Not what you needed?

February 27, 2007 10:23 AM

i am in a university campus at the moment and i am facing this problem 'a duplicate name exists on the network'. If i change the name of my computer and the workgroup how will i exchange information with the rest of the university workgroup?

Leo Notenboom
February 27, 2007 12:33 PM

Hash: SHA1

Change the name of your computer, not the name of your workgroup.

Version: GnuPG v1.4.6 (MingW32)


July 5, 2007 9:26 AM

Windows system error- a duplicate name exists on the Network". This could be because of a duplicate name used in the Network connection. Every computer should have a unique name in the network, in order to be identified in the Network. To resolve the issue, I suggest you change the name of the computer by performing the following:

1. On the Desktop, right-click MyComputer.
2. Choose Properties.
3. Choose the Computer Description Tab.
4. On the window displayed, click the Change button.
5. This will open another window.
6. On the displayed window, Type the new Computer Name.
7. Do not modify anything with the Workgroup box.
8. Click Apply, then O.K.

Michael Layden
July 5, 2007 4:12 PM

This can also happen if you have an ethernet connection, and inadvertently enable a wireless card at the same time. DHCP assigns two leases with the same name but different IP addresses. Solution is to disable the wireless, check ipconfig at the client, then delete the other lease at the server.

Cecile Dunbar
September 25, 2007 11:52 AM

An article at Stanford's School of Earth Sciences gives a reason why this might continue to happen.
Link to it here

October 9, 2007 7:05 AM

Actually, I had the same problem this morning when I got to work. I tried all means but none work. I decided to change my IP address and domain name.. Guess, what happened.. it worked perfectly and all is back to normal.. Thanks for your thread though.

Eldmar Korsnes
February 13, 2008 1:51 PM

I have worked/asked/searched this problem on our network for two - three weeks.

The solution was surprising and had nothing(?) to do with this error message.

By isoliting a small part of the network, using new cables and a new switch everything was OK, and I could continue from this.

What caused the error message?; a damaged cabletip(I don't know the English name) from the 3Com AP to the switch, tightly bundled cables, old equimment or a a pupil/teacher who has put a cable into the wrong connection. I am not sure, but my bet is the cable from the AP to the switch.

I hope this could be of help for some? Let me know - - -,

Jac Goudsmit
December 25, 2008 8:47 PM

Thanks! I had this problem because I configured a NAS device to have a device name that matched the workgroup name. The message popped up on each computer on the network as soon as they started up. Changing the hostname on the NAS fixed the problem.

March 28, 2010 10:17 AM

Thank you for the info. This solved my "duplicate name" problem right away. Just thought I'd point out how sensitive the computer names are: one of my computers was called "MACHINE" and the other was called "machine." I do realize that this is the same name but naively assumed that the capital letters versus the lowercase letters would be alright-it wasn't! After changing one the problem disappeared.

Thanks again!

May 7, 2010 4:17 PM

How can it detect a duplicate name with no network configuration whatsoever? I got this after a fresh install, first boot, before even installing the network drivers. Huh?!

May 21, 2010 3:40 AM

I was in trouble. Because when this msg was showing my internet speed was going down. Morever my ISP was also obscured about this problem. At last I googled the problem and came here.... WOW! how shall I thank to the writer of this post! My problem has gone. many many thanks.

July 8, 2010 3:17 AM

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!

July 17, 2010 2:01 PM

Thank you
It was so helpful

August 14, 2010 3:12 AM

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

December 28, 2011 9:22 PM

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.
February 4, 2012 10:22 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.

B. Trout
June 4, 2012 6:38 PM

Thanks Leo, it worked great!

mhke cloud
March 10, 2013 3:18 PM

thanks for the help, its good to know that there are persons like you who are willing to give advice to other people who are not knowledgeable with computers and yet willing to learn. thanks again and more power...

Jim Gambino
March 12, 2013 6:54 PM

This also appears in the eventlog when you have workstations or servers with 2 or more network adapters. I get this annoying message at least once a week because all of my computers have multiple network adapters. I have yet to see it really cause a problem, but if someone knows how to prevent this error from ever appearing in the Event Log even if you have many NICS on your machines let me know.

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