Solution : https://service.sap.com/sap/support/notes/497135 (SAP Service marketplace login required)
Key words :
remove existing entries, command line processor, dbdiff set source = '', dbdiff table notes, dbdiff table, table dbdiff, source column, sql command, terms dbdiff, system attempts
Related Notes :
33814 | Warnings of inconsistencies between database & R/3 DDIC |