Don’t vote twice. It will just give the Dims a reason to toss out Republican ballots across the country, even in districts where we won fair and square, and it will discredit us among independents. I will vote once, though my state’s Electoral Votes are a shoo-in for Biden. Maybe I can make some difference further down the ballot.
But if you follow Trump’s instructions you may indeed end up voting twice. Depends on what they do with the mail ballots after you’ve gone to the polls, learned it had not been counted and then voted.