Great game, was very fun and I did like the minimal aesthetic. I think it's interesting and cool that we both went for a similar core (swapping death & life worlds with platforming) but it went very different with gameplay & visuals.
I liked the dialogue but I think that repeating it exactly every restart of the level can get annoying
Initially I didn't realise that I could move the window into the other world (don't know if it was mentioned or I just missed it)
Sometimes I would die while holding a key, respawn to my clone and still be holding that key and that would kill me which would be annoying. Having a delay would help out with that.
It wasn't entirely clear the banners from the top where obstacles and not background, making that more clear would be great.
Music or even just some sound effects would help massively (can always find some free/creative commons music that would fit the game)
Overall though these are just small critiques and I thought it was a great game and really enjoyed it.