Unable to perfrom Nero's CD-DVD Speed on a DVD+R DL

I used DVD Decrypter’s ISO Write to backup a movie DVD (with copy protection) with a DVD+R DL 2.4X (CMC), the new DVD worked perfectly.

Later, I checked the new DVD quality with Nero’s CD-DVD Speed, it seems that NERO can’t recognize L1 layer, the scanning process stops in the half way. The strange thing is that Nero recognize the disc is a DL disc (from the disc info section), and it just stops at somewhere around 4 G. The same thing happens to DVDInfopPro.

I guess the copy protection causes DVDdecrypter to fill-in the protected sector with a dummy sector in between L0 and L1, Nero is not able to identify the dummy sector, so it stops there.

CD-DVD Speed works perfect with DL disc(burned from unprotected DVD)

Anyone knows other ways to do media testing on a DVD+R DL (burned by DVDDecrypter or other decrypter and ripping code softwares)