Extract webmin generated TAR files


I did the following:
Go to system -> file system backup -> add new backup

backed up from: /var/www/app/Controller
to: /var/backups/source-backup/test.tar
tape size: 300kb
and Split across multiple files? Yes

I run the backup and it backs up fine into: test.tar1, test.tar2, test.tar3 and test.tar4

I download to my computer via ftp and try to open these files in winrar, 7zip, it will open the contents of test.tar1 only and break, it will say “Unexpected end of archive”

Note: if you do not split the files, it will open fine, but i really have to split the files because i will be backing up an entire server and the file sizes will be huge as this here is just an example.

Any help is appreciated, thank you.