If you have a release which varies from what is in the database that qualifies as a unique release, you can use an existing submission as a template for your submission using the Copy To Draft feature.
First, you will need to navigate to the release history page. Click "Edit Release" from the appropriate release page.
From the release history page, click "Copy To Draft."
You will then need to confirm by clicking "Okay." From your drafts folder, click the "Edit / Submit" button next to the draft that you just added.
Here, edit the draft to match the release in your hand, make sure not to leave any bits such as barcode, country or date which may not match your release. Be sure all credits are accurately represented as well and that any credits or information on the draft which is not present is removed.
Upon completion of the release, make sure to either create a new master release or add it to an existing one if applicable. More information about that can be found Here.