It's very easy with DVDShrink and DVDDecrypter.
1) Install both programs.
2) Put movie no. 1 into the drive.
3) Start DVDDecrypter.
4) Set its mode to "File".
5) Click "File" -> "Decrypt"
6) Repeat steps 2 to 5 for movie no. 2.
7) Open DVDShrink.
8) Click "Re-author" button.
9) Find the copies of the DVD's on your hard drive with the "DVD browser" section of the program and add the movie titles you want into the "Re-authored DVD - Structure" section of the program.
10) Choose which titles, and which audio, video and subtitle streams will or won't be included in the DVD you're creating. (You should do this, to save space and reduce the amount of recompression that needs to be done on the movie(s) to fit onto the new disc.)
11) Put blank DVDÂ±R/RW/RAM/DL disc into drive.