Duplicate source.list error

Duplicate source.list error

how do I troubleshoot this :
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/
raring/partner amd64 Packages
(/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_raring_partner_binary-amd64_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/ubuntu/
raring/partner i386 Packages
(/var/lib/apt/lists/archive.canonical.com_ubuntu_dists_raring_partner_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems
doing sudo apt-get update does not solve this issue
i tried y-ppa-manager but it probably checks for duplicate ppas and hence
failed