After upgrading to 12.04 Gnome Classic amd64, I have multiple duplicate items, three each of "Conical Partners-software packaged by Canonical for their partners" and "Conical Partners-software packaged by Canonical for their partner(Source Codes)". This did not happen on my x86 upgrade.
This also shows up when updating by command line,
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ precise/partner amd64 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-amd64_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ precise/partner amd64 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-amd64_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ precise/partner i386 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/ precise/partner i386 Packages (/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_precise_partner_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems
...But running apt-get update does nothing
Here is /etc/apt/sources.list
# deb cdrom:[Ubuntu 10.04 LTS _Lucid Lynx_ - Release amd64 (20100429)]/ lucid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://mirrors.us.kernel.org/ubuntu/ precise main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://mirrors.us.kernel.org/ubuntu/ precise-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://mirrors.us.kernel.org/ubuntu/ precise universe
deb http://mirrors.us.kernel.org/ubuntu/ precise-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://mirrors.us.kernel.org/ubuntu/ precise multiverse
deb http://mirrors.us.kernel.org/ubuntu/ precise-updates multiverse
## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
# deb http://us.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ lucid-backports main restricted universe multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu precise partner
deb-src http://archive.canonical.com/ubuntu precise partner
deb http://mirrors.us.kernel.org/ubuntu/ precise-security main restricted
deb http://mirrors.us.kernel.org/ubuntu/ precise-security universe
deb http://mirrors.us.kernel.org/ubuntu/ precise-security multiverse
deb http://archive.canonical.com/ precise partner
deb http://extras.ubuntu.com/ubuntu precise main #Third party developers repository
# deb http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu natty main # disabled on upgrade to natty
# deb-src http://ppa.launchpad.net/ubuntu-x-swat/x-updates/ubuntu natty main # disabled on upgrade to natty
# deb http://ppa.launchpad.net/videolan/master-daily/ubuntu natty main # disabled on upgrade to natty
# deb-src http://ppa.launchpad.net/videolan/master-daily/ubuntu natty main # disabled on upgrade to natty
