Archive was packaged wrong

Images are greate but:
wget “http://localhost/components/com_mtree/attachment.php?link_id=845&cf_id=24” -O imagepack-ubuntu.tar.gz
–2017-10-07 13:52:34– http://localhost/components/com_mtree/attachment.php?link_id=845&cf_id=24
Resolving exchange.nagios.org (exchange.nagios.org)… 66.228.58.94, 2600:3c02::f03c:91ff:fedf:d653
Connecting to exchange.nagios.org (exchange.nagios.org)|66.228.58.94|:443… connected.
HTTP request sent, awaiting response… 200 OK
Length: 6702 (6.5K) [application/x-gzip]
Saving to: ‘imagepack-ubuntu.tar.gz’

imagepack-ubuntu.tar.gz 100%[=====================================================================================>] 6.54K –.-KB/s in 0.002s

2017-10-07 13:52:35 (3.98 MB/s) – ‘imagepack-ubuntu.tar.gz’ saved [6702/6702]

$ file imagepack-ubuntu.tar.gz
imagepack-ubuntu.tar.gz: gzip compressed data, from Unix
$ gunzip imagepack-ubuntu.tar.gz
$ ls
imagepack-ubuntu.tar
$ file imagepack-ubuntu.tar
imagepack-ubuntu.tar: gzip compressed data, last modified: Mon Oct 29 17:29:07 2007, from Unix
$ gunzip imagepack-ubuntu.tar.gz
gzip: imagepack-ubuntu.tar.gz: No such file or directory
$ gunzip imagepack-ubuntu.tar
gzip: imagepack-ubuntu.tar: unknown suffix — ignored
$ mv imagepack-ubuntu.tar imagepack-ubuntu.gz
$ gunzip imagepack-ubuntu.gz
$ ls
imagepack-ubuntu
$ file imagepack-ubuntu
imagepack-ubuntu: POSIX tar archive (GNU)
$ tar xvf imagepack-ubuntu
logos/
logos/ubuntu.gd2
logos/ubuntu.jpg
logos/ubuntu.png
logos/ubuntu.gif
$ ls
imagepack-ubuntu logos