Just added a script to github which takes care of duplicating the most recent duplicity backup files.
You can specify the amount of past backups runs. By default the last two full backups and their incrementals are copied, older files are automatically deleted (sliding window of most recent backups).
Use this script to add another level of redunancy in case that the main backup location fails.
The software, i.e. file naming conventions has been tested with duplicity version 0.6.13 (yes I know, quite old).
Usage examples
Copy with standard arguments (last two full backups and associated incrementals), older backups / other files at dst folder will be deleted:
./copy_duplicity_backups.py /mnt/src /mnt/dst
Show which files would would be deleted/copied without actually writing anything to disk:
./copy_duplicity_backups.py --dryrun /mnt/src /mnt/dst
Copy last 5 backups and associated incrementals:
./copy_duplicity_backups.py --nr 5 /mnt/src /mnt/dst
Limit size of dst folder to 5GB. Backups are copied until limit is reached:
./copy_duplicity_backups.py --maxsize 5000 /mnt/src /mnt/dst
Do not output anything – only in case of errors:
./copy_duplicity_backups.py --quiet /mnt/src /mnt/dst