Orson Pratt gives reason for discrepancy about angel's name.
Orson Pratt to John Christensen, 11 March 1876, Historian's Office correspondence files, 1856-1926, CR 100 394, Church History Library
You inquire whether it was the Angel Nephi or Moroni who visited the Prophet on the night of the 21st & 22nd Sept., 1823? As Moroni holds the keys of the Stick or Record of Ephraim, (See B. of Cov. pp. 201, 322,) we have reason to believe that Moroni was that angel. The discrepency in the history to which you refer may have occurred through the ignorance or carelessness of the historian or transcriber. It is true, that the history reads as though the Prophet himself was writing: but the Prophet was a slow and awkward writer; and many events recorded were written by his scribes who undoubtedly trusted too much to their memories, and the items probably were not sufficiently scanned by Bro. Joseph, before they got into print. The prophet often received visits from Nephi, Moroni, Peter, James, John (the beloved), John (the Baptist), Elijah, Moses, &c, &c, &c, the three Nephites, etc., etc. In giving the instructions which these angels imparted to him in a verbal manner, it would not be surprising that some of the hearers should in<n>ocently confound and intermix the names of the angels.