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Why do we get duplicate Computer Systems? | v8+

1 min read

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ITAM tools will always be subject to occasional, duplicate device records. All automated tools are bound by the data available to them and are impacted by the various ways that customers manage, clone, image & deploy their devices. The Miscellaneous > Duplicate Systems screen is your means of monitoring and processing possible duplicates that arise. Duplicate devices mean twice-counted software, etc., so periodically attend to your duplicates and track them on a health dashboard. Duplicate computer systems are archived with a right-click action on single or multiple records.

Miscellaneous > Duplicate Systems is a report of possible duplicate client records and is based on computer system records where there is a match between any one or more of the following attributes:

  • Computer name

  • Serial number

  • BIOS serial number

Computer systems with the same properties above will show up in duplicate systems.

Certero assigns a unique identifier to computer systems. When a computer is added to an Active Directory domain it is given a GUID (Globally Unique Identifier) by the domain. This is the unique identifier of that computer. In theory, this should be unique 'globally'.

Certero also assigns a GUID to computer records as part of the inventory process. This is stored in the Registry under:

HKLM\Software\Certero\Client\UID

For computers that are joined to the domain, the GUID assigned by Certero is matched to the Active Directory GUID. Note that:

  • If a computer is renamed and added to a new computer account in Active Directory this will create a new Active Directory GUID and a duplicate computer record arise in Certero.

  • If the existing computer record is renamed, then this will not result in a duplicate.

When rebuilding computers, re-imaging them etc., adding the computer to the same account in Active Directory will ensure a duplicate recorded is not created. If you are unable to add the computer to the same record, try disabling the Active Directory computer record rather than deleting it.

False Positives

Some manufacturers do not correctly populate the serial number or BIOS serial number correctly.  This can cause systems that are not actually duplicates to appear in the duplicates list. The following examples may show as duplicates and should be deemed as false positives:

  • Server blades in a chassis may all have an identical serial number but have a unique BIOS serial number.

  • Virtual machines (e.g. VMware) can all the same serial number from the hosting infrastructure or hypervisor software.

  • Computers built from components, sometimes called "White Box Systems" may be shipped with a generic serial number e.g. "OEM", 0000000 or 123456789.

  • Computers shipped from the manufacturer in the same batch can sometimes have identical serial numbers.

  • Computers where the motherboard has been replaced may have had an incorrect serial number applied to the new motherboard.

  • Computers with the same computer name. For example, a global organisation with multiple AD domains could have a computer in two regions with same name e.g. "RECEPTION".

Use the Manage button at the top-tight of the Duplicates screen to enter false-positive serial numbers. Devices with these serials will be filtered out of the list of duplicates.