Hello and welcome!
In the past I experimented with backing up the Duplicati sqlite files. This usually involved setting up a secondary backup job that backed up the database of the other job, since while a backup is running the job’s own database is being modified and may not be consistent.
But I abandoned that approach and think it is unnecessary. If you have json exports of your backup jobs, it’s very easy to recreate the job. Test recreation of the database. It should be fairly quick and not require any dblocks to be downloaded.
Also, after upgrading Duplicati and you have no problems after a couple days, feel free to delete the ‘backup*.sqlite’ files.