Betty, I wondered typographically that confusion between Archie and Artie could be a problem with handwritten transcription or more likely hot lead typesetting etc , or a computer read version of same, eg from eg newspaper like printing, or could it be difficult writing either name if one was used to writing in irish or latin etc. I have not run into a gaelic version
useing a gaelic dictionary online
https://learngaelic.scot/dictionary/index.
Archie= Eàirdsidh
Arthur= Artair ,
so I doubt the theory
I noted there are 35 entries for Murphy in the Tithe Applotment Books see
http://titheapplotmentbooks.nationalarchives.ie for Drumsnat, but alas none for Archibald or Arthur
and also no Murphy in Tydavnet Co Monaghan
There are no Sherry listed in the Tithe Applotment Books for Drumsnat and
Tydavnet Co Monaghan but plenty elsewhere in Co Monaghan
going earlier to 1796 Flax growers of Ireland, both names show enterprise
Murphy Henry Drumsnat Monaghan
Murphy John Tedavnet Monaghan
Murphy Laurence Tedavnet Monaghan
Murphy Patt. Tedavnet Monaghan
Sharry James Tedavnet Monaghan
Sharry Patrick Tedavnet Monaghan
Sherry John Tedavnet Monaghan
Sherry Thomas Tedavnet Monaghan
I noted the Sharry and Sherry spelling in same townland, was it the enumerator or the accent he was hearing or two enumerators
Finally it dawned on me i was staring at both names in the one parish
Good luck onwards