The UCS Manager dialog enables you to rename UCSs containing identical names. Identical UCS names may exist after an import operation if the user had previously selected Preserve original UCS name after an import operation in the Preferences.
When identical UCS names exist, the
Rename
Identical Names icon is activated in the UCS
Manager dialog (shown below).

You can rename identical names by clicking the
Rename Identical Names icon. The system
automatically renames all the identical names that exist in the UCS Manager dialog, using a numerator
(for example, UCS10_1 will become UCS10_2 and so on), as follows:

The system renames the UCS that does not exist in the Feature Tree (this could be the UCS of an imported part).