I take it back…just checked and to clarify:
The law says someone’s name can’t appear in more than one place on the ballot.
So, Rand Paul has until that particular primary to make up his mind which office he wants to pursue.
I suspect the gray area will be: is it the date he actually files to appear on the primary ballot, which is sometime in January of that particular year, or the actual physical ballots being printed that triggers the law.
My guess is the former.