Mapping &1 repeats mapping &4 for &2 &3

What causes this issue?

Mapping &V1& is used to define an import/export mapping for field/
attribute &V2& &V3&.
This has already been done using mapping &V4&.

System Response

It is not possible to use different mappings to import a field from
several attributes, nor to export several fields into an attribute, as
the result of this mapping is not defined.

How to fix this error?

Change the mappings so that a field or attribute is described by only
one mapping procedure.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.