The same ISO is attempted to be loaded twice.Virtualbox.xml wrote: <MediaRegistry>
<DVDImages>
<Image uuid="{4f454f9d-0ef6-4786-8d49-fb6e0c9954c6}"
location="C:/Users/jacek.brzezinski/VirtualBox VMs/JBRVM/JBRVM-disk002.iso"/>
<Image uuid="{ae4ab52f-6409-4807-ba98-06329b18966c}"
location="C:/Users/jacek.brzezinski/VirtualBox VMs/JBRVM/JBRVM-disk002.iso"/>
</DVDImages>
</MediaRegistry>
This "Virtualbox.xml" only has one of the ISO's.
Reboot your host.
Rename your "C:\Users\jacek.brzezinski\.VirtualBox\VirtualBox.xml" to "VirtualBox.xml-bad".
Then extract the zipped "VirtualBox.xml" into "C:\Users\jacek.brzezinski\.VirtualBox\"
Then try Virtualbox.