Front & Rear Screen Protectors?

G'day,

I've just purchased an iPhone 5S... It's still in the box...

I saw someone recently comment that they use a screen protector to protect their iPhone's screen from scratches, but also use one for the back of the phone, for the same reason - particularly as the phone resides in a hard case, and dust/etc becomes trapped inside the case and scratches the back of the phone...

Does anyone else do this?

If yes, do you just use a 2nd screen protector, or are there protectors specifically for the back of your phone?!

Thanks,