On your wedding day you will be signing several documents. One is the certificate of marriage. This certificate is a commemorative certificate and is one for you both to keep. As of March 2019, Births Deaths and Marriages are allowing celebrants to apply for your official marriage certificate on your behalf. All paperwork is now submitted online to ensure quicker turn around times. See below this clip explaining the process -
Video by Directors Edge
Alternatively if you wish to apply for your marriage certificate yourselves see below - To apply for your 'official' marriage certificate click here.
About marriage certificates You can use a standard marriage certificate as proof of your wedding for official purposes, such as changing your name on a passport or driver licence.
BDM can only issue a marriage certificate once the marriage is registered in Victoria.