De acordo com a lista de e-mails
you will have to manually exclude it ..
it holds your backup chains index files (table of contents of the backup repository). Caching them locally accelerates options like status and incremental backup and others. These operations need to know what is already backed up to work. If they are cached they do not need to be transferred and decrypted every time again and again.
.. ede
Para o resto, parece ser um bug de longa data .
No rastreador de bugs do Debian, eles recomendam
duplicity cleanup --extra-clean --force ....
Aviso : a opção --extra-clean
sugerida é perigosa e pode ser muito difícil. Ele torna os backups inacessíveis por meios usuais .