no you dont you add all files to convertx and it will automatically join them and create 2 titles in the menu. You can them use dvd2one to create a seamless movie only. Need more info on what files are on the cd
Open convertx drag both files into window set up under settings and convert
I make multiple title movies using convertx regularly
If you did want to join crop (ie timers

) or in anyway change the files I use TMPGenc xpress