No it doesn't cause any problems at all. If I remember correctly it's just an additional .frf file (that may not be the correct name) under the .dll file in your plugin folder. So if you have 20 T-Racks plugins your now going to have 20 .dll files and 20 .frf files. If you un-install Mixbus (you won't) I believe you have to manually delete these files.
This is some kind of identifier for Mixbus. I'm not sure why it needs it, but it does.
They also have a good forum and good support. I have installed it 4 or 5 times now without any issues. When they have an update...the installer removes the old version and installs the new version.
If you have anymore questions...I'll be glad to help if I can.