I have been trying to copy this movie and 1click get to 30-50% and stops. I noticed that this movie uses a dual layer format. I tried again and checked off dual layer option. It copied to 100% and then tried to burn but I didn't have a dual layer disk. If the movie is in a dual layer format then it has to be burned to a dual disk, is this correct? I seem to be learning something new every time I burn a movie lately. If I am wrong in my thinking please help.

No, you do not need a DL disc. When copying this movie, make sure the "Dual Layer" and the "DTS" boxes are empty.
This is what 1click does, it takes a big file and compresses it enough to fit on a regular size DVD.

Which version of 1Click you using? Regular or Pro?

(And to be totally honest here, I had to use CloneDVD2 to get this one to copy correctly. Not to say that 1Click won't do the trick, I just wasn't willing to sit back and try to find the right combination of what needs to be added or deleted to get a good back-up.)

What if any other options are you trying to select?

I burned it to DL with no problems

yes you can burn to a DL disc as long as you check the DL setting, but no you do not need a DL disc to make the copy.