That is an interesting theory about the children dying before a name could be decided on. It is too bad there isn't a civil record to check it against. I've never come across something like this, even on the civil side. I'd be curious if anyone ever saw both, if they were close in date.
I was rather struck by the missing "fil" on the first entry. This is partly what made me think of the possibility of a stillborn child, delivered in early term. I didn't think stillborns were officially baptized, but I wonder whether everything was always strictly orthodox in a country church. I can almost picture a really distraught family moving a priest to perform the ceremony.
I have noticed another odd irregularity pertaining to Glenbeigh, albeit many years later, in about 1867, but one harder to judge since it is an index entry and not an image. One of GG grandfather's brothers almost seems to have been married twice, to the same women, in two parishes, Glenbeigh and Dromod. Unfortunately the Glenbeigh date seems to be unreliable ( it doesn't match).
The groom and bride have the same names, Bridget Sullivan and Patrick Connor. One of the witnesses has the same name too, Denis Shea, but the other is different. Of course, they are common names, but I think they are the same people. It was a consanguineous marriage too. I thought perhaps it may have been the banns, mistaken for a marriage (this part of the register, one could guess is severely damaged) but the sponsors names being there is a bit odd.