Because of the considerable time between the two dates, I suspected an irregular marriage in Edinburgh being followed up by the kirk session. I found this in the minutes of the Kingsbarns kirk session:
Kingsbarns 20th March 1791 being sabbath
After prayer sedt. The Minister and all the Elders
The Minister informed the session, that William Hog servant to Mr
Erskine of Cambo had given into him a Certificate of his Marriage with
Jean Alloway and that him and the Woman was to Compear before
the Session this afternoon they being called compeared, was then interrogate
by the Minister if they were Married, Answered they were Married, the
Minister then exhorted them to live mutually together as becomes Married
persons, the Certificate of their Marriage was produced by the Minister
the tenor whereof follows, Ednr 11th Febry 1791, That William Hog Day
labourer in Edinburgh and Jean Alloa, Daughter of James Alloa late
Farmer at Preston Miln Parish of Buncle were regularly married by me
date & place above mentioned is attested by Jo. Kemp, Minr
The Sedt closed with prayer
[sedt = sederunt, Latin for they sat. Used to introduce a list of those present at a meeting, or used to mean the meeting itself.]