DCR - How to reflect new records created in external db to Notes DB?

If new records are created in external db(Access, SQL, etc.), how will this be reflected in my notes db?

If I click Import External Records(from Designer)again, all previous are duplicated in Notes.

How to get just new documents?

Subject: RE: DCR - How to reflect new records created in external db to Notes DB?

The LEI Redbook contains a discussion of this.