Whether a copy of the reference table should be made for fuzzy match index construction and subsequent matching. It is strongly ...

Whether a copy of the reference table should be made for fuzzy match index construction and subsequent matching.  It is strongly recommended that a copy always be made, otherwise unpredictable output may result if the contents of the reference table change during package execution (or between executions if reusing a fuzzy match index).  If this property is set to false, the reference table must additionally have a clustered index built upon an integer identity column.