Kitten Eating Adult Cat Food?

I have a 2 year old cat and a 2 month old kitten who like to eat each other's food. Is there any way to prevent them from doing this or is it okay for the kitten to eat adult cat food? 

I don't know what food you are feeding your adult kitty.  If it's a good quality food then it's fine.  I personally think that often the idea of a kitten food is more a marketing thing.  I know here in the States the high quality foods don't make a kitten food, all of their foods are all life stages.

My adult kitty is rather picky and has a hard time transitioning to "good quality" foods, he current eats Boots & Barkley dry food. My only concern is the size of the kibble, which is bigger than kitten kibble, but the kitten seems to not have a problem with it. 

On sites like petfoodtalk.com, it seems like there's a lot of horror stories about quality dry foods causing urinary issues and crystals (specifically Blue Buffalo?) Neither of my cats have had or currently have any urinary issues, and both drink lots of water so would a switch still be necessary? 

The dry vs wet is a debate that goes on and on.  I personally think that wet is better because of the extra water and generally it has lower carbs particularly the pate type foods.  So much of it is genetics too, we have all either had or know of a kitty that lived to be 20 and ate cheap kibble all their life.  If you want to try transitioning to canned food here is a good article about doing it  http://www.thecatsite.com/a/transit...-to-a-new-type-of-food-canned-raw-or-homemade

If you are free feeding kibble then there really isn't a way to keep the kitties from eating each others food.  Most people do leave a little kibble out for the young kittens.  Adults can be fed meals and I believe that it is healthier for them to have meals.  There is a link in the above article on transitioning a free fed cat to meals.