This is a symptom of an improperly cloned operating system install. you should run sysprep on the machine in order to generate a new machine SID. Duplicate SID Error in windows server 2012 







I got this error while adding/joining my windows server 2012 R2 to my a domain. it was due to wrong/improper configuration of server (this Vm server was cloned and was SID was not configured properly.


Follow the step mentioned in mentioned article : Article ID: 243267 

HOW TO: Find and Clean Up Duplicate Security Identifiers with Ntdsutil in Windows Server 2003

Start Ntdsutil

To start Ntdsutil: 
  1. Click Start, and then click
    Run.
  2. In the Open box, type
    ntdsutil, and then press ENTER. To access Help at any time, type ? at the command prompt, and then press ENTER.

Look for a Duplicate SID

  1. At the Ntdsutil command prompt, type security account management, and then press ENTER.
  2. At the Security Account Maintenance command prompt, type
    connect to server
    DNSNameOfServer
    , and then press ENTER. Connect to the server that stores your SAM database.
  3. At the Security Account Maintenance command prompt, type
    check duplicate sid, and then press ENTER. A display of duplicates appears.

Clean Up a Duplicate SID

  1. At the Ntdsutil command prompt, type security account management, and then press ENTER.
  2. At the Security Account Maintenance command prompt, type
    connect to server
    DNSNameOfServer
    , and then press ENTER. Connect to the server that stores your SAM database.
  3. At the Security Account Maintenance command prompt, type
    cleanup duplicate sid, and then press ENTER. Ntdsutil confirms the removal of the duplicate.
  4. At the Security Account Maintenance command prompt, type
    q, and then press ENTER.
  5. When you are finished with Ntdsutil, type
    q, and then press ENTER.

hope this Help. thanks

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