Some systems need irreversibleness from a legal viewpoint. Image a voting machine for instance: at what conditions should it accept that the same person votes a

Some systems need irreversibleness from a legal viewpoint. Image a voting machine for instance: at what conditions should it accept that the same person votes again ? In reality there must be situations where voiding a first vote and casting a second should be allowed. But for one, is it even possible IRL in most situations, for instance during a single day voting window ? For two, how would you make that an option that can be used at the level the reversing decision is taken, while also protecting from abuse from bad faith actors and corrupt elements ?