The second I read “I tried turning the starter over, and noticed that there was zero compression” my head went to valve timing.
I also knew the sound you heard... not the typical oscillating rewREWrewREWrewREWrew but the disconcertingly smooth and higher pitched rrrrrrrrrrrrrrrrrrrrrr :-)

My guess would be that, in a stacked configuration, the lower rotor is always working in the air disturbed by the upper rotor and would necessitate some form of compensation (e.g. run more collective on the lower rotor or possibly even different rotor design). Not sure if this would introduce inequality and…

I knew what you <i>[i](i)meant(/i)[/i]</i>!

You’ve clearly never carried a garden torch around for any length of time have you... or gone camping... or used a gas lantern.

LOL... stock photos cost money - Torch nabs them straight from Google Images;

I should’ve clarified - manual trans Subaru given the shift fork.
Looks pretty close to me;

My first guess is almost any Subaru?
No idea what model but I imagine they’re very similar and hard to tell apart anyway...