MIDI file export weirdness

When I have a single flow, I can export to a MIDI file without any problem.
With two flows, both are played simultaneously in the MIDI file as if it had two channels.

If I export to WAV, I get normal behavior - both flows played one after the other.

Does Dorico currently provide any control over which flows are exported to a MIDI file?
Ideally, I’d like to choose a single flow to export at a time. Each flow is a hymn and I’d like to export them to separate files. I can do this successfully by copying each flow into a new project, but this is a lot of extra work.

Thank you,

In the forthcoming 1.1 update each flow can be exported to a separate MIDI file.