Having 2 DVD drives or 1 DVD-ROM/CD/ and 1 DVD burner is okay. When you have a lot going on you can't afford to have one of your drives take a crap on you. This is only if you're dedicated to burning a DVD/CD with the one and or using the other for watching movies/playing PC games. I just like to have a backup because we all know that DVD/CD drives all die out sooner than later and always when you least expect it.
Most people don't need to get 2 DVD drives because they think the one drive can take the load for all things(and in most cases it can) but if you plan on doing anything more than a few operations(and using it on a daily basis) I would go with 2 to be on the safe side. They are cheap anyways depending on the brands you get. I usually stay in the $30-$50 range and I never go wrong. They last me at least 30X their weight in gold.

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Cooler Master HAF 932(Full Tower)
Intel® Core™ i5-750 Processor
(8M Cache, 2.66 GHz)
ASUS P7P55 PRO Motherboard
Samsung S27A550H 27"
(Class Widescreen LED HD Monitor)
5 WD scorpio black HDDs
2 DVD writer/burners
WIN 7 Ultimate X64
8 GB of RAM

"The only problem with troubleshooting is that sometimes trouble shoots back."