Just released v1.9.10, which should fix the underlying problem with force_stream_order (explained in detail by @justindujardin in this post). The only case where a glitch may still be possible with the current implementation is if you hold down a hotkey and rapid fire – but that should also be a pretty unusual scenario.
Good point, I'll add a note to the docs for now! We definitely want to have a clearer link between regular datasets and session datasets in the future so Prodigy can automatically remove "orphaned" session datasets – but this may require some changes to the database model.