Need Help With Joining DVDs

Hi. I tried joining "The Good, The Bad, And The Ugly 2-Disc DVD Edition" with DVD Shrink, so I can burn them in a dual layer disc.

The problem is DVD Shrink joins them as two separate movies instead of just one. And since they are joined as two separate movies, once the first part reaches its end, the movie pauses as it goes onto the second part.

Is there any DVD re-authoring software that can join two DVDs as one?

Looking forward. Thanks in advance. :)

ConvertXtoDVD is what I would use but if you want to keep menus with features I not sure if that will work but it is worth a try!