This one is best labeled as the HM360 but with a metal tube fuselage.
It was never build. The HM380 made this design no longer needed.
Clearly this plan was based on a HM360-plan.
In old emails i found this tiny part of a HM361 plan.
Translated: "This elementary two-seater has the purpose to train a builder of a single-seat HM360 into piloting a Flying Flea. Let's consider it as a single-seat for a heavy weight pilot or a two-seater trainer in jockey-style (Passenger sitting just after the pilot with back of pilot touching the front of the passenger)."