I guess you know you can make disc copies with just one drive by copying the original to a hard drive image file. That's the way I do it, but then I don't make many copies. If you have two drives on the same IDE channel it's probably no faster than using one drive.
I prefer the simplicity of only one drive in my computer. If something goes wrong with the reading of the original, I don't end up with a coaster. And if the burn turns out badly, I can try another burn using the hard drive image.