Mounted volumes appear as devices in Filebrowser

Hello there,
the issue is basically just a nuisance, not a real problem, but as far as I am concerned it is a bit odd.
I use

Ubuntu 16.04 Linux pa-tux 4.9.0-040900-generic #201612111631 SMP Sun Dec 11 21:33:00 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
Docker version 1.12.5, build 7392c3b
Docker-compose version 1.9.0, build 2585387

Based on these Instructions I moved my docker installation from /var/lib/docker to [My Home]/docker. But instead of setting a symlink, I used a daemon.json in /etc/docker/ to point to this directory and it all works perfectly fine.
But now when I open my filebrowser it shows the mounted volumes from [My Home]/docker/devicemapper/mnt under devices (like phones or usb-sticks)

Basic knowledge on Ubuntu and Docker I possess, but nothing too deep, so now I am wondering whether this is normal behaviour to be expected, is it a bug, can I turn this off somehow, have I found a “divine receipe” and am the first one to ever experience this ? :smile: