If by chance they don't accept DD's, you should be able to go to the Guest Services office in DTD and exchange DD's for cash. Check the directory for the location. Its tucked away on the side of one of the buildings and many people don't realize its there. You can buy park passes there too. We usually stop there on our arrival day to get our passes so we don't have to wait in line the next morning at one of the parks.
Steve