As far as we know, snakes do not have the capacity to form friendships with other snakes. Your snakes do not "sleep" together - they both curl up in the same place because they both want the temperature and privacy represented by that one spot. I would seperate the snakes before they get much older. I've heard of people being surprised when they wake up one day and find snake eggs, having been sure that their snakes were too young to breed. :shrugs: If they're both male, they could fight. And even if they don't breed or fight, keeping them together may present stress and feeding problems.
Although some people use a heat lamp, I believe that a heat mat is preferred. The snakes' digestion will benefit from the belly heat.