Goodbye Roxio Toast, Hello Burn!
Free, and does what you want with way less crap than Roxio Toast. To save DVDs to ISO images (which you can then use as virtual masters for duplicating) choose the Save As CD/DVD Image option. It will produce a .cdr file. The file extensions can be confusing: .cdr (Burn plus some other Mac programs), .toast (Roxio Toast), and .iso (the rest of the world) are all identical — the files produced are bit-identical to each other. So you can change the resulting file extension from .cdr to .iso if you want. The resulting file can be used as a disc master on virtually any burning program, Mac, Windows, or Unix.