I am not familiar with Victoria’s BDM documents from that era, but I am familiar with NSW BDM documents from that era….
So, I offer the following comments …
When a couple marry, the officiating minister/officer requires the bride and groom and their witnesses to sign several times in various registers and on official documents. Then the Bride is handed the signed certificate, which has those original signatures. (Notice that the wife needed the document, afterall she was the one who was about to change her surname) .
The document that Vectis2 holds is not that “Bride’s copy”, but a copy from the Vic BDM (ie from ‘Office of the Government Statist’) in Melbourne and was issued 25th October 1898. FOUR years after the marriage... And, at the top left, there's a Duty Stamp that was franked …. FIVE shillings ... not a penny, but 5/-. If this were a NSW document from that era I would be thinking “Possibly obtained to support a divorce suit or child maintenance or a warrant for arrest of husband …. Wife desertion ” ….(Not possible to seek to commence a divorce suit/or a maintenance order/etc without first providing the court with proof of the marriage in the first instance). This document (25 Oct 1898) was likely sought by someone physically attending and requesting the official document, and if so, likely knowing the date of the marriage and the surnames of either or both the bride and the groom. (Add, 1898 and NSW BDM registers were not indexed for clerical use within the Register General's Office, I don't know if Vic BDM registers were indexed, but I think the "Pioneer" and "Federation" indexes date from volunteer efforts in the late 1920s and early 1930s.)
Cheers, JM