You can read the bootable CD into an ISO "image" file using the free ImgBurn program and then use the same ImgBurn program to burn the bootable ISO image file onto a DVD+/-R.
That copies the bootable CD exactly, without giving you the chance of adding anything to the DVD.
If you want to add stuff to the bootable ISO image before burning, the Shareware program UltraISO can do that fairly easily.
There are also other more complicated methods that involve copying the boot-info and making a new CD/DVD with the extracted boot-info and whatever files you want included.
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