[Ubuntu-PT 7394] Erro ao actualizar

[Aerrege]

Vivam!

Venho novamente pedir ajuda :-( Desta vez, é sobre um erro, sempre que
faço actualizações (clicando no ícone respectivo do painel):

W: Duplicate sources.list entry http://archive.canonical.com/
lucid/partner Packages
(/var/lib/apt/lists/archive.canonical.com_dists_lucid_partner_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/
lucid/partner Packages
(/var/lib/apt/lists/archive.canonical.com_dists_lucid_partner_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/
lucid/partner Packages
(/var/lib/apt/lists/archive.canonical.com_dists_lucid_partner_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.canonical.com/
lucid/partner Packages
(/var/lib/apt/lists/archive.canonical.com_dists_lucid_partner_binary-i386_Packages)

Obrigado.

ARG