No, sorry, this is incorrect. If you don't have the park hopping option, you CAN'T go into a second park that same day. Disney's almighty computers will not allow that to happen.
Let's say you go to MK today. You can come and go in and out of MK today as much as you please. But if tonight you decide to check out Epcot, you won't get throught the turnstile.
Non-hoppers entitle you to one theme park per day. So in other words, you can't buy a 2-day non-hopper today and use it up by going to 2 different parks today.