lucid-proposed updates showing also when not enabled

[okap]

Hi
i'm using ubuntu lucid.
apt-get suggests me ubuntu updates from the lucid-proposed repository
even if it's not enabled in my sources.list
Perhaps it was enabled in the past but now it's not.
this is my sources.list:


deb http://it.archive.ubuntu.com/ubuntu/ lucid main restricted
deb http://it.archive.ubuntu.com/ubuntu/ lucid universe
deb http://it.archive.ubuntu.com/ubuntu/ lucid-updates universe
deb http://it.archive.ubuntu.com/ubuntu/ lucid multiverse
deb http://it.archive.ubuntu.com/ubuntu/ lucid-updates multiverse
deb http://archive.canonical.com/ubuntu lucid partner
deb http://security.ubuntu.com/ubuntu lucid-security main restricted
deb http://security.ubuntu.com/ubuntu lucid-security universe
deb http://security.ubuntu.com/ubuntu lucid-security multiverse
the directory sources.list.d is empty
I tried to reinstall apt and start with an empty /etc/apt but those packages
(for instance mysql-client-core-5.1 version 5.1.41-3ubuntu12.1)
keep showing on update-manager

How can i avoid that unwanted packages ?
Thank in advance

[okap]

my error the packages I wanted to avoid are in lucid-updates