Oliver Cowdery’s supralinearly inserted Nephi was written with weaker ink flow, which suggests the possibility that this insertion was due to editing—as if Oliver somehow thought that the phrase “blessed art thou” needed to be followed by a name. Of course, the reader already knows that the Lord is speaking to Nephi, so there is no motivation for adding the name except that the original text read this way. The correction may have occurred when Oliver read back the text to Joseph Smith and the ink in the quill was running out or had dried out somewhat.
Elsewhere the text has examples of “blessed art thou” with and without a following name. In all these cases, there is no evidence of a scribe correcting the manuscript by either deleting or adding a name after “blessed art thou”. In four out of ten cases, there is no name:
Excluded from this list of “blessed art thou” are three cases for which no name can be given. In these cases the narrative itself does not provide a name for the person (the servant of the vineyard in Jacob 5:75 and king Lamoni’s queen in Alma 19:10, 12).
Summary: The supralinearly inserted Nephi in 1 Nephi 2:19 probably represents the reading of the original text since there is no strong motivation for Oliver Cowdery to have added the name after “blessed art thou”.