I am trying to determine if these are one and the same or two different couples. The answer is yes and no and maybe
To start with, marriage dates, and places, taken from Scottish birth certificates are not always accurate. I have seen families where 5 or 6 Scottish birth certificates give all give slightly different details for parents' marriage and none of them turn out to be 100% correct.
Where the couple Catholic? if so they might have been married before 1864 (say 2 Oct.1863) and civil registration of Catholic marriages only started in 1864.
Are you getting the 25 Oct. marriage from FamilySearch? if so, not all records are in those extracted records.
https://familysearch.org/pal:/MM9.1.1/FG8Y-XQKThere seem to be lots of Martin Wallaces in Galway in the 1901 census (years later than the marriage you are looking for but gives an idea of the popularity of the name).
One point that doesn't eliminate the marriage you found is that the extracted LDS births doesn't show the couple having children in Ireland after your couple has moved to Scotland.
Are Martin and his wife in 1911 census? if so, married women were asked how many years married. Do you have birth certificates for all the children? this may give you different dates. Have you traced your couple in each possible census record (in case they happen to have relatives staying with them)?
Last point is the locations in both marriages. The townlands of Inverin & Killannin are about 20 miles apart (by road). Inverin (Inveran) townland is in the civil parish of Killanin and Poor Law Union/registration of Galway. The LDS records sometimes give the registration district but other times the sub-district without clarifying that in the record.
So, at the moment the answer is maybe, maybe not but certainly keep it as a posssibility.
