Copy NAV dvd Porsche

Hello all , i was wondering of a confirmed way to copy Navigation DVD's in general.. as it always when u try to copy them it shows that the dvd has only 30 - 40 MB data i read a couple of threads on internet and mostly not working ... now i have a porsche middle east navigation map dvd and i want to copy that to another dvd , anyone knows a way ?
thnx.