I can see how it would be confusing.
The EVH are only offered at one park at a time... but I think occasionally they may have morning hours at one park and evening hours at another. So if you don't have park hopper tickets you would have to choose which one. I think you can find out in advance which ones are when... I will try to find the site. You would want to know ahead if you can so you can plan your time and your meal reservations.
The good news is you can usually upgrade your tickets once you get there if you decide you want the park hopper later.