> having the same structure and files. The client's
> server address is changed on each new access by a
> round robin method.

Err - you are mirroring the same IP address each time, are you ? (ie. when
updating, you are using the same IP address ?)

If not, the redownload is perfectly normal: the site host is seen as another
one. This should be the case for 3.3X series, too.

By the way: did you try --continue to continue the mirror ? Another hint is to
use -qiC1 when updating, after erasing doit.log (--continue will attempt to
get previous settings from this file - if you specify the site's address and
options again, you have to remove this file)