Missing sound with fluidsynth when two notes overlap

[beicause]

Describe the bug
When using fluidsynth track and two notes overlap, the second note will miss a part of sound, only has sound within the overlapping.
This bug is more noticeable when using violin/sax, etc.

To Reproduce
Steps to reproduce the behavior:

1. Add audio output, fluidsynth track and midi track.
2. Draw two notes, press shift and drag to make them overlap.
3. Play from the start of the first note.

Expected behavior
The second note shouldn't miss sound.

Desktop (please complete the following information):

• OS: openSUSE Tumbleweed
• Desktop: KDE

[devloop0123]

That's not a bug, but just the way note-off works. When a note-off is preceded by two note-ons for the same note, which one should the note-off apply to? Length-of-note is not part of midi messages.