We had a problem with one workstation, where "something happened" and the user could no longer get past Zenworks Agent login window during login. The technician re-installed agent on workstation and this caused duplicate devices to appear in the zone, one named HOSTNAME and one HOSTNAME-GUID. Not a very big surprise there, such thing has happened before. Both devices were deleted from ZCC and we expected one new device to appear with name HOSTNAME, but it appeared with name HOSTNAME-GUID. Multiple attempts of deleting this device and re-registering with 'zac reg -g' have been made, and each time the device appears in ZCC with its new correct GUID appended to the hostname. In services-messages.log on the primary server, the following is seen:

Sep 15 13:36:32 thor [2838]: WARN: [09/15/2014 13:36:32.662] Registration Web Service Novell.Zenworks.Registration.DEVICE_NAME_CHANGED Device name already existed, changed to hostname-11c6b303036e09408f6c2aca017a7a40 while attempting to register host : HOSTNAME.
It seems that the old device still exists somewhere in Zenworks database, but I can't figure out how to find it. I've tried from ZCC to perform advanced search by, for example, device serial number or MAC address, and I find only the new device named HOSTNAME-GUID. Any ideas on how to solve this?

Both the managed device and primary server are running ZCM 11.3. Workstation is Windows 7 SP1 x64, server is SLES11 SP3 x86_64.