I can only suggest (personally) 2 possibilities...
1) The bride was previously married and is either windowed or divorced, but is getting under that Surname.
2) Her mother was married again, sometime after the bride was born, and the marriage certificate reflects the current Surname of the mother & step parent.
There's other variables to consider, but I just listed the 2 common ones I've personally encountered.
When it comes to information, that's a bit dated, you should consider situations that's the norm back then and is typically not the norm today.
I hope I had explained this okay via text... :-)