Internal: Error due to repeated generation of a function selection

What causes this issue?

A second attemp was made to generate a function entry for the same key.
There is probably an error in the program flow of one of the selected
functions.

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?

You should contact your systems administrator. If the error occurred
when executing a standard function the error must be investigated by
SAP.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.