Sorry you are right, I didn't think about that. My plan (when I expend the game) is to add profiles, like having 3 slots of save, so several people can play without losing their progress. For the current game, you can go back pretty fast once you know how to solve the puzzle, so I hope it is not too bad.
I realized it wasn't as bad as I thought it would be, but would still be nice to have a prompt to prevent an accidental overwrite. Thanks so much for your response! The game is still very solid in gameplay and is something I would recommend to friends!