There should be an option to force HTTrack to consider the server as
case-insensitive, to avoid downloading the same file many times for each
variation of the case.
In some cases the same file can be downloaded hundreds of times.
e.g.
/Dir1/subdir/index.html
/Dir1/subdir/Index.html
/Dir1/Subdir/Index.html
/DIR1/subdir/Index.html
/dir1/Subdir/index.html
/Dir1/Subdir/index.HTML
/Dir1/SUBDIR/index.html
etc.

While I agree that there's no way HTTrack could know on it's own, but that's
why there should be an option to do it.