The quantity table to be calculated contains duplicate entries

What causes this issue?

The quantity table for which the Quantity Conversion Interface (QCI)
calculates quantities contains duplicate entries for at least one unit
of measure.

System Response

The system stops processing. Although the QCI can calculate a quantity
several times consistently, this error indicates a problem of the
calling application that has to be resolved.

How to fix this error?

Contact your system administrator

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.