Let's say something like this is being returned when attempted to federate a node in a WebSphere deployment manager (dmgr) using the addNode.bat (Windows) or addNode.sh (Linux) command.

ADMU0027E: An error occurred during federation ADMU0034E: The node/cell name of
           the node being federated with addNode must have a different name
           than the cell name of the Network Deployment manager node:
           Cell01; rolling back to original configuration.

As the error suggests, cell name of the node you are attempting to federate into the WebSphere deployment manager (dmgr) is exactly the same as the cell name of the WebSphere deployment manager.

/opt/WebSphere/AppServer/profiles/Profile01/bin/addNode.sh dmgr.example.com 12345 -includeapps

Unfortunately, this basically requires you to delete and then re-create the profile that has the same cell name as the WebSphere deployment manager. The manageprofile.bat (Windows) or manageprofile.sh (Linux) script and be used to delete the node profile.

/opt/WebSphere/AppServer/bin/manageprofiles.sh -delete -profileName Profile01

And then re-create the node profile, ensuring the cell name of the node profile is different than the cell name of the WebSphere deployment manager.

/opt/WebSphere/AppServer/bin/manageprofiles.sh \
-create \
-profileName Profile01
-cellName myTotalUniqeCellName

At this point, the profile should now have your totally unique cell name.

~]$ ls -l /opt/WebSphere/AppServer/profiles/Profile01/config/cells/

drwxr-sr-x 16 admin users 4096 Nov  5 21:19 myTotalUniqeCellName

And you should now be able to federate the node profile into the WebSphere deployment manager without getting ADMU0027E.

/opt/WebSphere/AppServer/profiles/Profile01/bin/addNode.sh dmgr.example.com 12345 -includeapps