> I have a html page "mysite.article.php?id=xxx"
> It is referenced from three pages, it was saved
> three times: [articlecf8b.html, article25d0.html,
> articlefa7a.html] However the three files must be
> the same!
Not necessarily. The ID=xxx was different so the content may be the same to
totally different there is no way to know. If you know then put in a filter.

> I think if the file was saved
> [article.php.id=xxx.html], it will be saved only
> once.
Question marks and equal signs are not valid filename characters on some
platforms, so httrack uses a hash of the of the id=xxx and append that to the
filename articleHHHH.html You can also generate names like article_ID-xxx.html
with a User Defined Structure -
<http://httrack.kauler.com/help/User-defined_structure>