That’s simply not true. It has nothing to do with Trump. The ballot was always set up this way, and the vote that will be counted to determine the primary winner is the at-large vote. No one NEEDS to vote in both places. By the way, what is so confusing about voting for your candidate in both places where his name appears?
You want confusing, try Pennsylvania, which has always had a “beauty contest”, where you vote for the presidential candidate. There is also a vote by district for delegates, who are listed under their own names, without any indication of who they are pledged to, which did determine the delegates to the convention. So, you could vote for your candidate in the beauty contest, and they would show as the winner of the state, but, unless you know the delegates pledged to your candidate, you could end up voting for someone else’s delegates.
Maybe in some districts in Ohio but never in mine and I have been voting here since I was old enough to vote.