Buying a Bunk Bed With Double Bed A bunk bed with double beds can make the most of a small bedroom space. The most secure bunk beds are secure and robust. Find sturdy guard rails that prevent children from falling off or falling into mattresses. This solid wood bunk bed is Greenguard Gold certified and can be divided into two separate beds. The stairs are wide enough to accommodate adults and teens. Size When looking for a bunk bed with double beds size, size is a key aspect to consider. Many children grow rapidly and may require you to buy a new bunk bed prior to them outgrowing the one they have. When selecting a bunkbed it is important to consider the kind of mattress. Twin over twin bunk beds double on top beds are the most popular bunk bed configurations. These bunk beds consist of two twin-sized mattresses stacked on top of each other. They are ideal for children sharing bedrooms.