I got this problem when trying to update using sudo apt-get update

W: Duplicate sources.list entry http://archive.ubuntu.com/ubuntu/ saucy-backports/multiverse amd64 Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_saucy-backports_multiverse_binary-amd64_Packages)
W: Duplicate sources.list entry http://archive.ubuntu.com/ubuntu/ saucy-backports/multiverse i386 Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_saucy-backports_multiverse_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems

This is my souces.list :

# deb cdrom:[Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)]/ saucy main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu saucy main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu saucy-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://archive.ubuntu.com/ubuntu saucy universe
deb http://archive.ubuntu.com/ubuntu saucy-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://archive.ubuntu.com/ubuntu saucy multiverse
deb http://archive.ubuntu.com/ubuntu saucy-updates multiverse

## 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://archive.ubuntu.com/ubuntu saucy-backports main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu saucy-security main restricted
deb http://archive.ubuntu.com/ubuntu saucy-security universe
deb http://archive.ubuntu.com/ubuntu saucy-security 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.

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu saucy main
# deb-src http://extras.ubuntu.com/ubuntu saucy main
# deb http://archive.canonical.com/ saucy partner
# deb-src http://archive.canonical.com/ saucy partner

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

## Major bug fix updates produced after the final release of the
## distribution.

## 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.

## 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.

## 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://archive.ubuntu.com/ubuntu saucy-backports 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.

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.