You may have heard that you should vote twice to make sure that your vote gets counted, however it is llegal to vote twice.  From NBC News:

"Despite what Trump has suggested, experts say trying to vote twice is a bad idea. First, it's illegal to vote more than once. Second, it isn't some sort of voter insurance method. "It's a bad idea. And it's also not a fail-safe," McReynolds said."Anybody who goes and attempts to do that is going to be turned over to the district attorney or potentially attorney general," she said. "It is a crime to attempt to vote twice or to do it. Those penalties aren't small. They're felonies in most cases."

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