You must make sure your vote is counted (see title of this post). The best way to do that is, after voting, to shove your ballot in a poll worker’s face and demand he count it now. He may protest saying they do the counting now, so be persistent. Then watch him as he counts and says, “I count one vote from you.”
What you can then do is say, “No! It’s two votes!” If you’re intimidating enough, maybe you can make him agree and get two votes.

When I fed the ballot into the official vote counter/shredder, I shook my fist at it. Hope that worked. It was all I could think of at the time.
Even better, volunteer to assist the voting, and correct any “mistaken” Leftie ballots.
Dammit, I already voted! I ‘coulda used that particular piece of advice this morning Frank, but NOOOooooo, YOU had to wait to now to tell me!
…
…’course I coulda thought of that myself…
…dammit.