You can clone a DVD even without auxiliary software. Recent Windows versions include a DVD burning solution. Follow the guidelines provided by the program. If you have an older version than Windows 7, you can download Imgburn to rip the DVD to an ISO. Beware of spyware and pay attention to the download page and the installation wizard. Uncheck the Conduit Search Protect box and select Custom Installation. Do the same for Tuneup Utilities. Then you can quickly create an ISO that you can burn using a single DVD burner.

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Source:
http://www.fixedbyvonnie.com/2013/12/how-to-copy-dvd-another-dvd-using-single-dvd-drive/#.VA4KS6NaM8E

Disks and hard drives have wear and tear problems so DVD backup is important. Mac is very popular and there are ways to duplicate DVD on Mac too. Mac includes a built-in application to copy and burn a disc, so you can use that to duplicate a DVD. You can select the DVD file, hit Duplicate or Burn to Disc. Another method allows you to duplicate the DVD by pressing the Utilities icon in the Application folder. Double-click on Disk Utility and select the source and destination file. Magic DVD Ripper for Mac is also useful to remove the DVD protection and watch it on any device.

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Source:
http://mac.magicdvdripper.com/duplicate-dvd-on-mac.htm