Duplicate of DVD-1

A week or so ago there was a long discussion on how to make a duplicate of the 'dreaded double-layered DVD'. I made one. It appeared to be ok and it booted just fine but now in trying to do an install with it, it says that it can't read the package material so it can't suggest what to install. And in fact, there is nothing to install because it appears that there are no packages. The ARCHIVES.gz is there as well as all of the other files. The only thing I can think might be wrong is that the DVD wasn't given a label in the process and therefore the install may not think it has the right DVD. Has anyone tried to install using a duplicated dvd? Thanks