Yes Nick, that is how it is expected to work. The name you give appears inside the xml - "MiniToolBar.MapperState.en.xml". "mapToolbarYYYYMMDD########.xml" is time stamped. Every time you change something in the map customization, you will have a new "mapToolbarYYYYMMDD########.xml" created. It is 3rd party designed by Sync Fusion, we can't do much about it.
Regards,
Shweta