playing backed up DL games

[calabreseboy]

i have backed up a dual layered disc of mine, the game is champions of norrath, it works fine when i play the original disc it doesnt stuff up or jam or anything...but when i play the copied version it starts up fine and plays fine until i reach about halfway through the game and then on loading a new level it jams...i checked that it actually burnt all the info from the original to the blank media and it did...im using a sony dru 700A DL burner use verbatim DL media my ps2 version is 30002 (think means version 2) and i dont know what mod chip i have...is anyone able to help me out and tell me what is the problem