DVD-RW is a bad idea to begin with. They are much more expensive than ordinary one-write DVD's. The process of writing is substantially slower. Blank one-write DVD's are only about $0.30 each.
You should be able to copy one CD or DVD to another with just one drive. Simply open the window on the source disk and click copy. It should then copy the contents to your hard drive temporarily. When it is done, it will ask you to put the blank disk in, then write to it.