The coding that you are looking at refers to the Mormon Church microfilm copy of the original OPR
MONRO DONALD JONET STEWART/ 15/03/1743 346/ 20 281 Dull
So 346 is the parish number, 20 is a film roll number (there were all spliced together to make a single microfilm roll) and 281 is a page number.
If you are lucky enough to have a resource centre that holds the microfilm you can find the entries more easily. Thus the 1743 entry is on page 281 of the OPR and the 1746 is another 11 pages on, which is what you would expect from the entry dates.
However, without looking at the actual wording of these two original entries it is impossible to say whether these are the same entry (which would be odd). Yes, the Dull OPR does have some entries re-written at a later date by the registrar, but to have given an erroneous date would be unusual, and secondly re-writes are normally of whole blocks of marriages so there should be a block of secondary entries with the wrong dates.
Knowing what Dull parish OPR can be like we suspect that entry will merely say 'both of this parish', but the baptisms should all give where the child was born. The Logierait OPR usually gives more detail.
Without being able to see all of the original entries it is difficult to give further advice.
Throth (
www.borenich.co.uk)