I have a pair of marriages both on 3rd September 1814, I would post the images but probably get told off.
1) In the parish of St Saviour, Southwark,
Thomas Small of this parish, Batchelor, and Sophia Denman of this parish, Spinster
Married in this Church by Banns by me, W. Mann Chaplain [also have image of the banns]
Signatures Tho: Small, Sophia Denman. Witnesses Wm. Moore, Lucy Moore
2) In the parish of St James, Westminster,
Thomas Small Esquire of the parish of St James, Westminster [not 'of this parish'], and Sophia Drake Widow of this parish,
Married in this Church by Licence by me, James Glen Curate
Signatures Tho: Small, Sophia Drake. Witnesses Wm. Moore, Lucy Moore
Register 1) is an original but 2) has all signatures in the same hand so is some sort of copy.
I tended to assume Sophia was known in one parish as unmarried and in the other as a widow; and perhaps Thomas wanted to be sure he was legally married; or some such explanation. Or that the second entry was not of a second ceremony but just a record that the parishioner had married elsewhere (but then was there really a licence?)
Very mysterious.