SAP Customer Checkout update issue

Hi everybody

I'm trying to update CCO from FP6PL06 to FP8PL16, however, the process get an issue and the update can't finish.

The log show the next message:

ERROR 23505: The statement was aborted because it would have caused a duplicate key value in a unique or primary key constraint or unique index identified by 'UNQ_IDX_BUSINESSPARTNER_EXTERNALID' defined on 'BUSINESSPARTNER'