In general, when you get a new DMA radio, it's wisest to dump the pre-programmed contents first, then save them away. Then when you are ready to start your own programming, use the 'Erase All Systems and Settings' button for your first attempt. Thereafter, you can decide whether to replace or add...best regards..Mike
When ever I go to upload a new "code plug" to my 396XT, I always save it to my laptop with the date in the file name, that way if I want to go back to a previous code plug, I have it on file.