FYI - Almost every commercially released DVD (Movies that is) are, and have always been, dual layer. This has been part of the DVD specification from the beginning. As for whether or not a unit will play a dual layer DVD recorded by someone else on a home PC, the jury is still out. That being said, the people that make recordable dual layer discs claim that they CAN be read by virtually every DVD player made.
I leave it to you.