"update Existing Download" with vervion 3.30+ works in a 
weird way...

As I watch the number of files downloaded, I will see the 
number of files in the downloaded folder shrink 30%, then 
it will grow back to what it was before the Update attemp.

Also the number of bytes saved is the same size as the 
original complete site download, so it seem it will 
redownload everything every time...

The files are static and will always have the same 
filename, so there is no reason to redownload everything...

here is a log extract : 
No files purged 
HTTrack Website Copier/3.32-2 mirror complete in 19 minutes 
58 seconds : 4303 links scanned, 3608 files written 
(207624512 bytes overall), no files updated [206614087 
bytes received at 172465 bytes/sec]
(14 errors, 0 warnings, 3590 messages)