Storage server already exists - illegal duplication status 242 when configuring tape library

Storage server and tape storage are like 2 separate entities.. no relation..

If the illegal duplication error message is for the storage unit then its probably just that there is some storage unit in the configuration which already exists with the older name in Nbu config..

now you mentioned that you tried deleting the robot and then did a complete reconfiguration of devices in nbu.. storage unit does not really have any kind of reference to any serial number or anything.. simply double click on the older storage unit and change the density and the media server and select the newly configured robot number on the storage unit and you are good to go..

you simply need to change the storage unit manually to point to the new robot number or then delete the existing one and nbu would be able to add the new storage unit..

Looking at the naming convention of the storage units you have highlighted its clearly the default names picked up by the configuration wizard in nbu

emdlove

Please see the reply to your other post over here: 

https://vox.veritas.com/t5/NetBackup/How-do-I-completely-remove-old-library-from-NBU/m-p/851420

PS:
Please provide feedback over here as well?
https://vox.veritas.com/t5/NetBackup/File-Read-Failed-13/m-p/845721