I've encountered the same problem. Wheezy AMD64 update fails with message:
"trying to overwrite shared '/usr/share/doc/libxrender1/changelog.Debian.gz', which is different from other instances of package libxrender1" -- To UNSUBSCRIBE, email to debian-x-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/552c19dd.2020...@gmail.com
