It contains some code packages written by other authors:
tarfile.py by Lars Gustabel - Python module for reading/writing tar files.
The Launchpad, for hosting the duplicity project.
The Free Software Foundation, for hosting duplicity mailing lists and web site.
Mikael Moshir for sending his interesting paper on encrypted backup with the rsync algorithm. Duplicity didn't end up using his scheme, not because it wasn't very good, but so volumes could remain processable with, for instance, rdiff.
Peter Ehrenberg for many helpful comments/bug reports.