old age
i saw this movie years ago and don't remember it too well but i do have one bit of ridiculousness to point out.
lets use bob for example: all people die of old age if not sooner, and so all of the bob's will eventually die out one by one until there is only one bob left which would give him super-mega strength.
this type of thing would happen all the time since there will always be a point in time when only one remaining "bob" exists with each set of persons.
i didn't look too hard, sorry if this was discussed before