"SQL0803N One or more values in the INSERT statement ... not valid because the primary key ... from having duplicate values for the index key. SQLSTATE=23505" when trying to import data from flat file

Symptom

Example #1
Standard Error
Source: System.Web.Services
Description: System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Exception: [DB2/NT64] SQL0803N One or more values in the INSERT statement, UPDATE statement, or foreign key update caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "2" constrains table "<username>.XDB16" from having duplicate values for the index key. SQLSTATE=23505
at Microsoft.VisualBasic.ErrObject.Raise(Int32 Number, Object Source, Object Description, Object HelpFile, Object HelpContext)
at ControllerServerCommon.RaiseErrSrv.RaiseException(Int32 number,
Exception ex)
at FrDImportBT.clsExtImport.DoImport(String sGuid, String sUser, Boolean bCaseExpVal, Int32 lBatchId, String sSpecName, String sStructureType, String sPrompts, Int32 lLLocale, Boolean& bError, Int32& lError, String& sErrorMsg, RecordSet rsFileDataAndInfo, RecordSet& rsRecon, RecordSet& rsLog, Boolean bIsExcelImport, Int64& lImportedRows)
at Cognos.Controller.Proxy.CCRWS.clsExtImport_DoImport(String sGuid,
String sUser, Boolean bCaseExpVal, Int32 iBatchId, String sSpecName,
String sStructureType, String sPrompts, Int32 iLLocale, Boolean&
bError, Int32& iError, String& sErrorMsg, DataSet dsFileDataAndInfo,
DataSet& dsRecon, DataSet& dsLog, Boolean bIsExcelImport)

Example #2
Source: System.Web.Services
Description: System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.Exception: [DB2/NT64] SQL0803N
One or more values in the INSERT statement, UPDATE statement, or foreign key update caused by a DELETE statement are not valid because the primary key, unique constraint or unique index identified by "6" constrains table "FASTNET.XDB18" from having duplicate values for the index key. SQLSTATE=23505
at Microsoft.VisualBasic.ErrObject.Raise(Int32 Number, Object Source, Object Description, Object HelpFile, Object HelpContext)
at ControllerServerCommon.RaiseErrSrv.RaiseException(Int32 number, Exception ex)
at FrDImportBT.clsExtImport.DoImport(String sGuid, String sUser,
Boolean bCaseExpVal, Int32 lBatchId, String sSpecName, String sStructureType, String sPrompts, Int32 lLLocale, Boolean& bError, Int32& lError, String& sErrorMsg, RecordSet rsFileDataAndInfo,
RecordSet& rsRecon, RecordSet& rsLog, Boolean bIsExcelImport, Int64& lImportedRows)
at Cognos.Controller.Proxy.CCRWS.clsExtImport_DoImport(String sGuid, String sUser, Boolean bCaseExpVal, Int32 iBatchId, String sSpecName, String sStructureType, String sPrompts, Int32 iLLocale, Boolean& bError, Int32& iError, String& sErrorMsg, DataSet dsFileDataAndInfo, DataSet& dsRecon, DataSet& dsLog, Boolean bIsExcelImport)