Replicating update download site

[Gianni Bragante]

I would like to create a local distribution point for Fedora updates inside
my network. I have replicated the official ftp site where updates rpms and
other files are available and shared it as ftp site in our internal network.
However running up2date -u from a newly installed PC I get the following:

Red Hat Update Agent v4.1.16
Copyright (C) 1999-2002 Red Hat, Inc.
Licensed under terms of the GPL.
[root at sbiorcl06 rhn]# up2date -u

Fetching package list for channel: fedora-core-1...
Fetching ftp://sbits03.incasgroup/FedoraC1/i386/headers/header.info...
Fetching package list for channel: updates-released...
Fetching ftp://sbits03.incasgroup/FedoraC1/i386/headers/header.info...
Fetching Obsoletes list for channel: fedora-core-1...
Fetching Obsoletes list for channel: updates-released...
Fetching rpm headers...
Name                                    Version        Rel
----------------------------------------------------------

All packages are currently up to date

The same result is obtained with the graphical interface.
Why? How can I avoid downloading the same RPMs several times?

Thanks
Gianni Bragante