I'm not seeing where he called you a liar. You put out a hypothetical that people could vote twice based on your being sent more than one ballot. You didn't actually vote twice so there is nothing to call you a liar about. Disagreeing with a possible scenario doesn't mean he is calling you a lair. As far as someone submitting multi ballots they do register receiving your vote so any duplicates wouldn't be counted.
It is true for income tax errors and it's true for lying under oath. I'm presuming it's true for all else because it makes sense.
A lot of people are saying how weak it is. It might be the weakliest thing in American history. It's probably the weakliest thing in the world.