Dual-layer discs should play back on any player. Most films are in dual-layer format to fit all the extras on it. If you look at the back of films, they'll say something like "DVD-9 dual-layer format may trigger a slight pause" near the bottom. The only problem you might have is whether your DVD player is compatible with +, - or both formats. A lot of players now work with both but some older ones will only accept one or the other, such as the Panasonic I've got downstairs will only take - discs.