I just found this nifty little feature tonight with Nero Recode. I use a combination of DVD Region Free 3.62 (CSS Copy Protection works with Recode 2), DVD Decrypter and Nero Recode 2. Well, I wanted to try putting 2 movies on 1 disc so here is what I did once I saw the option.
I decrypted the first movie to the hard drive with decrypter. Once that is done I put the second disc in my 451S so it could be read and left DVD Region Free take care of the copy protection on it. Next, Open up Nero Recode 2 and Remake the DVD. Once that is done Open the first DVD with the Import Title option and bring whichever one you want in first and drag out the main movie. Do the second one next (of course) off the DVD/hard drive and then click Next and start the process like normal! Works great! Get a bit extra compression but it's a neat future I wasn't aware of.