How can it be proven that they DIDN'T vote for Cochran? - that's the rub. You can't prove it either way, so if there are more wrongly cast votes than the margin of victory, then there might be grounds to call a new election.
How can it be proven that they didn’t vote for McDaniel? That’s my point. What happens if it is shown that a sufficient number of votes were illegal? I do have a serious question: what happens next?