Hm, well. I did download it again to give it a try, but it seems like i mistook the "on release" implementation of jumping for a bug :O Sorry! I guess it is made that way because you have to "charge" for the super jump?
But i think that is still a thing that makes me a little uncomfortable with the controls :/ Sometimes i like to "time" double jumps by holding down spacebar until the 2nd jump. Idk why, but jumping on release of spacebar was a little irritating to me.
Edit: I just read the latest comment from HedbergGames and i guess they did a way better job explaining that issue^^