sources duplicate problems while updating [closed]

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http://askubuntu.com – Possible Duplicate: Duplicate sources.list entry but cannot find the duplicates? W: Duplicate sources.list entry http://ppa.launchpad.net/gnome3-team/gnome3/ubuntu/ precise/main i386 Packages (/var/lib/apt/lists/ppa.launchpad.net_gnome3-team_gnome3_ubuntu_dists_precise_main_binary-i386_Packages) W: You may want to run apt-get update to correct these problems I get this message while updating. I searched the apt list in /var but I don't THINK there is any duplicates. The files of gnome3 team are only these: ppa.launchpad.net_gnome3-team_gnome3_ubuntu_dists_precise_main_binary-i386 (HowTos)