I have found a birth certificate which I am 99.9% confident is correct. Can anyone tell me if the birth certificate includes the mother's maiden name?
Yes.
The reason I ask is I have found the parents marriage but there are three entries, all on the same page, with the same (correct) details for the groom but the bride has three different surnames but the right first name?
Unlike England, Wales and Ireland, where a reference is to a
page in the registers and several entries can have the same reference, every birth, marriage and death registered in Scotland has a
unique reference number. Moreover, again unlike England and Wales, the GROS reference number is the same as the reference number used by the local registrars.
So if the reference for the groom is the same, then it's not three different marriages, it's just one marriage indexed three times.
If a woman marries more than once, the second and subsequent marriages are normally indexed by her maiden surname and by all her previous husbands' surnames.
When you get round to looking for her death, it should be indexed by her maiden surname and by all her husbands' surnames, and the death certificate should tell you the names and occupations of all the husbands as well as the full names of both her parents, including her mother's maiden name.
And the marriage certificate will tell you the full names of both sets of parents, including the couple's mothers' maiden names, and the birth certificate will tell you the date and place of the parents' marriage.
PS: First venture into Scottish records
You will find that the civil registration records are far more informative than the English and Welsh ones, but statutory registration in Scotland only started in 1855, and the church records up to 1854 are not always as informative as one might wish.