This is the special features of Record New in DM200 which can save the user time and space on the disc. DM200 will compare the data from the same file source to see if the data already recorded on the disc is the same as the data to be recorded. If they are duplicates, such files will not be listed on the file selection for burning onto the disc. DM200 will not change, modify, or delete any file on the data source (i.e. camcorder, camera, or iOS devices).