FamilySearch.org has an online database of estate records from across the state that span 1663-1979. Thanks to a collaboration between the NC Genealogical Society (NCGS), the NC State Archives, and volunteer indexers, the database is being made available online at https://familysearch.org/search/collection/1911121.
At the time of this writing, not all the counties were complete, so please consider helping out! Contact the NCGS for more information. Meanwhile, if you’d like to see a list of Duplin County records so you can browse, rather than have to search, view the document below.
Index to Duplin County, North Carolina Estate Files 1663-1979 by Taneya
If you’re unable to view the document, you can see it online here.