It appears that the UUID of a virtual disk (virtualmachine.config.hardware.device[2001].backing.uuid) can be changed as long as the respective VM is powered off. If the VM is powered ON then the ReconfigVM_Task API gives error: The <unspecified file> is locked.....
The API AnswerVM() works fine and the existing disk with duplicate UUID is added to the VM successfully. However each time VM is powered on the same question is promted to the User and thus its not a good solution.
Is anyone aware if the virtual disk UUID (virtualmachine.config.hardware.device[2001].backing.uuid) can be modified while VM is in powered ON state ?