It is certainly possible to burn with two dvd burners at the same time with a modern computer. Having two identical burners is not something I've tried though, and makes this a slightly more interesting proposition.
I use a free burning program called ImgBurn. Most of the regulars here do also, as it is a very fine program. If you don't have it, and wish to try it, download it from this page: http://www.imgburn.com/index.php?act=download
Click on any of the mirror links.
I'm sure ImgBurn will recognize both burners. If you are burning dvd-video, ImgBurn will recognize this and set the file system correctly for you, so if you get a message from ImgBurn asking to change a setting for you, let it do so.
You will need to run two instances of ImgBurn at the same time. Once you have started a burn, that particular drive will no longer be available for use, so only the second drive will show up to burn the next disc.