Plz help with Cats eating each others food

I am pretty much going overboard about this but I have two cats that I feed twice a day: Dry food in the morning same type of food just different amounts bc one is about 5 months and the other is just over a year. So at night I feed them fancy feast which for the kitten it’s the kitten type. They eat out of their bowl which it’s not anymore bc it’s been so bad I tried to see if switching their bowls to see it it would stop it. But they literally eat their own food for 5 minutes and then go right over to eat the other’s… Someone please help with this it is so frustrating and I don’t want this for the sake of their health and my money bc most times they don’t even finish… IT IS DRIVING ME INSANE!!