You can save your time with me by ignoring those kind of micro details, there is not "a lot" of anything in the Libertarians, their greatest victory, their electoral highlight was in 1980 when they tried to stop Reagan, even then in their strongest showing in history, they couldn't reach a million voters.
What percentage of atheists are you claiming voted libertarian that year? What percentage of atheists are you claiming to have voted for the Republican party in any year?
I don't know, but they are part of the many holes I have put in the claim that religiosity directly correlates to conservatism.