with Fleas (or any mignet type tandem wing) you have some quirks to be aware of that come from using the secondary effect of rudder as your roll control ... it is POSSIBLE with very aggressive and out of phase use of rudder to stall both front and rear wings on one side at the same time while the other side is still flying ... you roll and rotate SPECTACULARLY ... but that's not usual ... that's what you test during flight test of the the buggers ;-)
That's really very interesting, thanks for the post.