mirror command strange behavior

[agowa]

For some reason, lftp is uploading more data than the source has?!?
I have a 3 TB HDD, and I was uploading all the files from it to an FTP server using mirror -R --verbose --loop --parallel=10 --continue --no-symlinks --no-perms --no-umask --no-empty-dirs --depth-first /mnt/hdd /backup/hdd

And when I run jobs it shows strange stuff like:

[0] mirror -R --verbose --loop --parallel=10 --continue --no-symlinks --no-perms --no-umask --no-empty-dirs --depth-first /mnt/hdd /backup/hdd  -- 2.5T/6.3T (39%) 17.41 MiB/s
 \mirror `**1**'  -- 1.3T/222G (100%) 15.77 MiB/s
  \mirror `**1**/**2**'  -- 580G/131G (100%) 15.77 MiB/s
   \transfer `**1**/**2**/**3**' 
        `**3**' at 390067232 (2%) 15.77M/s eta:15m [Sending data]

I have no clue what lftp is doing here at all.

Edit: Now we're at -- 4.5T/9.1T (49%) 1.27 MiB/s, does anyone know what is happening with the stats? I checked the destination files and they look good, it looks like this issue only affects the reported stats.