For some reason, you have two volume 25's: duplicity-full.20111018T090402Z.vol25.difftar.gz and duplicity-full.20111018T090402Z.vol25.difftar.gpg.
Delete the difftar.gz one and try again. Does that work?
For some reason, you have two volume 25's: duplicity- full.20111018T0 90402Z. vol25.difftar. gz and duplicity- full.20111018T0 90402Z. vol25.difftar. gpg.
Delete the difftar.gz one and try again. Does that work?