I used the command netdom computername /add:newname.domainname.com to add a second name to a server running Windows 2008 Server R2. After restarting the server, I had DNS "A" entries for both names. In addition, the second name was added to HKLM\SYSTEM\CurrentControlSet\services\LanmanServer\Parameters\OptionalNames, which I believe should have taken care of any NetBIOS resolution.

From my Windows 7 workstation, I can ping both names and running net view on both names reveals the same list of resources. From Windows XP, I can ping both names, but net view only works on the first name. Running net view on the second name returns:

System error 52 has occurred.

You were not connected because a duplicate name exists on the network. Go to System in 
Control Panel to change the computer name and try again.

What do I need to do to make the second name usable from XP clients?

Update: I was able to resolve the problem by adding the REG_DWORD key DisableStrictNameChecking = 1 to HKLM\SYSTEM\CurrentControlSet\services\LanmanServer\Parameters, then restarting the Server service. However, I do not understand why this was necessary.