Object entry exists more than once; sort and compress first

What causes this issue?

You want to delete one of several identical object entries in the
current request/task.

System Response

This is rejected, since it is not clear what system behavior would be
correct.
(Should one or all entries be deleted? If key entries are assigned to
the object entry, should these be deleted, even if there are still
duplicates of the object entry?)

How to fix this error?

In the hierarchical request overview, choose "Request/task -> Object
list -> Sort/compress" to remove redundant object entries.

Error message extract from SAP system. Copyright SAP SE.