Pretty fun! I really liked the Music and Sound Effects of your game. Something I found myself doing a lot was constantly jumping just because I liked the sound that went with it. The mechanics are pretty good for a platformer although I agree that the double-jump could be tweaked a bit.
I saw the comment saying that they encountered the phantom double-player bug. I don't know how I managed, but I was able to produce a triple-player bug while a fourth one was flying throughout the levels (I think exiting to the menu and re-entering the game might've had some influence to it). Oddly enough I think that fourth pill finished the game for me because mid-way through one level the victory screen popped up for me. It was pretty quirky if I do say so myself.
Regardless, I enjoyed playing this! Nice work!