Can i copy files from one dvd-r onto another to copy the disc?

Are you using Windows? Are you using OS X?

Copying all the visible files may work. Try it.

In OS X, you can find this method listed in the Help menu of Disk Utility when you search for "copy DVD":
Open Disk Utility. Select the DVD. Click the "New Image" icon at top. Format should be "uncompressed, DVD / CD master". After you save the image, eject the DVD. Double-click the image file. In Disk Utility, select the mounted image, and click the burn icon.

Yes. You can have a try of DVD-Cloner for Mac.
Step 1: Insert the source DVD disc and run DVD-Cloner for Mac.
Step 2: Select the "Copy a DVD movie to a DVD±R" copy mode.
Step 3: Select a copy mode.
Step 4: Affirm the copy configuration
Step 5: Reading movie data
Step 6: Insert the target DVD±R/RW and burning will begin.
Step 7: Complete!
For more information about DVD-Cloner for Mac, please go to http://www.dvd-cloner.com/dvd-copy-for-mac.html