Data Domain: DDMC or DDMS cannot add DDR hosts due to duplicate UUID

DDMC or DDMS cannot add DDR hosts because of duplicate UUID.
DDMC reports an error such as:  Host dd11.emc.com is already being managed as dd22.emc.com.
DDMS (System Manager) reports an error such as: "cannot add DD_managed-host, host exists already".

This issue is triggered by hostname re-use on a Data Domain that is a part of a DDMC or DDEM inventory.  DDMC and DDMS use the UUID of a DDR for identification.  We have discovered that if a Data Domain system s hostname gets inherited by another Data Domain, the local UUID remains in the registry.  We have identified this behavior in a few scenarios:
 
When a Data Domain is added to a DDMC and DDMS inventory, we use the UUID to check if the system is in the list.  A hostname is retired off of one Data Domain but then later added to another Data Domain/DDMC controller.  The UUID is still mapped to the hostname causing an error message that this DDR is already managed/ already exists.

There is only a workaround for this issue which is resetting the UUID. 
 
First, identify there is a duplicate UUID instance:

Autosupport: In the DDMC or DDMS controller's autosupport, grab a list of the UI inventory under protocol.gui.ddem.inventory. Identify a duplicate UUID in the inventory list. You can also search by config.local.node_uuid.

Once the Data Domain duplicate UUID is discovered, remove the UUID registry from the Data Domain that you are not able to register.  This action can only be done with the command-line interface and requires SE privilege.

SE## reg remove config.local.node_uuid

NO OTHER ACTION IS REQUIRED. The system identifies no UUID is set and assign a new one.
Now go to your DDMC/ DDMS controller and try adding the Data Domain to its inventory.

If the issue still persists, collect a support bundle and contact Dell Support for further assistance.