opening second MSCZ file causes "previous session quit unexpectedly"
I use MuseScore 3.6.2 portable on Win10. I configured my portable MuseScore to open MSCZ files on double click by "open with", navigating to my portable MuseScore and checking "always use this program" (or the like, my environment is German so the wording in English might be slightly different).
When I double-click an MSCZ file it opens correctly in MuseScore 3.6.2 portable.
As soon as I double-click another MSCZ file "The previous session quit unexpectedly. Restore session?" pops up. In case I click "No", two instances of MuseScore 3.6.2 portable are running, one showing the first and the other one showing the second file. In case I click "Yes" also two instances of MuseScore 3.6.2 portable are running, one showing the first file, the other one showing file1 and file2 in two different tabs.
It is confusing and unclear what has been restored and which files to keep.
Expected behaviour: The second file shall be opened in another tab within the already running MuseScore. No error message shall be displayed.