This won’t really work. A given Duplicati job is tied to a particular destination. It’s not just the database.
Incremental backups
Duplicati performs a full backup initially. Afterwards, Duplicati updates the initial backup by adding the changed data only.
What this means is that the unchanged data is expected to be in the backup, and it won’t be if you use a different drive. There are some forum posts from people who’ve tried to set up a USB drive rotation, but there’s still a need to have a backup per drive. One can create the near-clone by Export, Import, and edit.
Beyond that it becomes a question of how you want to schedule your multiple drives, and how to prevent accidents if you don’t rotate on schedule. You can search for forum posts on this. One example is below: