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  Would it be possible for Trump to file twice in every state as both an independent and a Republican as a sort of loophole? In that case his application would be on time, regardless of which direction he needs it to go. I imagine anyone else doing that would tank their chances in the primary, but I doubt it would hurt Trump much.
context: The article you linked pretty much explains everything.
  When it comes to the presidential election, most states don't have absolute "sore loser laws", they just have filing deadlines that make it less feasible to run for one party's nomination and then drop out and run again as an independent. But even in the states with sore loser laws or early deadlines, there's always the chance of fighting in court to secure a spot on the ballot.