https://userapps.support.sap.com/sap/support/knowledge/en/3530305
3530305 - Resolving Duplicates in the SNAP Table During System Conversion to SAP S/4HANA | SAP...
During the Data Transfer Import (DT_IMP) phase of a system conversion to SAP S/4HANA, the following issue occurs: The phase is unable to create a unique index...