Unexpected quitting of MuseScore 2.0.3 rev:3c7a69d

When quitting I reopen at last state (3 open files) I get 3 files with different file names (presumably copies of the originals). But when I try to save any edits I get permission denied. I had not noticed these files were different versions initially. Can't see the point of this sequence of events and may be something I did so reporting it anyway. MacBook Pro latest OS version.

GIT commit: 3c7a69d