Definitely not cheating; that's exactly how you should play the puzzle! :) It's all about listening and comparing, and listening and comparing again. If you're playing in "normal" or "easy" mode feel free to also make use of that button on the right, which will play your attempt in the row so far so you can compare it to the puzzle before you submit your attempt.
My partner (who finds these puzzles more challenging) does this but still often completes the puzzle in more than one guess because they just want to test out how accurate they were on the first try and make use of the grey/yellow tiles to get closer to the answer, haha.
I think the point is that not all people can tell if the 2 melodies are the same (tone deaf?) but I agree it’s too easy that way. Maybe remove the option to replay your own melody before submitting.
My partner (who finds these puzzles more challenging) does this but still often completes the puzzle in more than one guess because they just want to test out how accurate they were on the first try and make use of the grey/yellow tiles to get closer to the answer, haha.