i was just curious cuz i bought a 25pack of memorex dual layer dvd+r's today for $50, and would like to know how long these discs usually last? are they of the same quality of store bought dvd discs? i noticed on the back cover of some store bought dvd's it says at the bottom dual layer so was wondering if they are the exact same discs im buying as blanks? do blank dvd discs last longer than blank cd-r's? thanks for the help boyz and girlZ!!!