Record of the Rust Family, published 1891, p. 13, lists two sons of Henry Rust (PGM 1637) of Hingham, Mass.:
In a footnote on the same page, the author adds: "The record, as here given, is just as it appears in Hubbard's Records of Hingham, copied by the author from the original. He however believes that the Benoni that died should have been Benjamin but entered Benoni by mistake."
I think "Hubbard's Records" refers to what is now called "The Hobart Journal," reproduced in NEHGR 121 in 1967. As far as I can tell, Peter Hobart's journal is the only surviving record for Hingham before about the 1660s, and secondary sources all trace back to it. NEHGR describes (pp. 3-7) the provenance of the journal in detail — notably, the oldest known physical copy of the journal is likely a reproduction of Peter's journal, hand-copied and then continued after Peter's death by his son David. NEHGR also details two previous transcriptions whose editors made alterations, e.g., standardization of dates and spellings. The compiler in 1967 strove to reproduce the original faithfully, including old-style dates and spelling and punctuation variations.
NEHGR 121 p. 18 transcribes the son's baptism as:
1646 ... Aprill ... 5 Ben-oni Rust bapt
NEHGR 121 p. 22 transcribes the son's death as:
1649 ... October ... 23 Ben=oni Rust dyed
NEHGR 121 is paywalled, but I found a hand-copied version of Hobart's Journal available for free online, and it too says the child baptized in 1646 was Benoni.
I've found other secondary and tertiary sources online, such as this printout at FamilySearch, naming the baptized child as Benjamin. I don't know if that might have originated with one of the other Hobart transcriptions, but it's definitely out there.
Assuming, as I am inclined to do, that NEHGR is a more trustworthy transcription of Hobart's journal, I think the author of the Rust genealogy had it almost right: the baptism and death refer to the same child, but he wasn't Benjamin, he was Benoni all along.
Does this seem reasonable and if so, should Benjamin/Benoni be merged into one profile with a good Research Note?