Data ID has already been used by &

What causes this issue?

The external data you want to analyze are stored in the performance
data base with a name key. This key can be freely selected in the range
between 'A1' and 'ZZ', if not already assigned to other external data.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Select a different name ID in the range between 'A1' and 'ZZ'.

Error message extract from SAP system. Copyright SAP SE.