Back ups are only good if you have a safe place for them. There is no reason to make a back up and then leave it laying about the office without ever using it again. I have back ups of many of my important software in my safe. But I do not have back up disks for any of my Operating Systems. My XP, Win2k, and Win98 disks are safely stored in a draw where they can be stolen at a moments notice.
I have a safe but fear that it would be the ONE thing that any would be house burgler would spend time stealing. So anything important is not in it. I have however placed a small neutreno bomb in it that will detonate 30 minutes after the safe as been removed from its mountings without the use of the proper disarm code.
Seriously, I can see no reason to have more than one back up of anything and only then if you properly take care of the original and use the Back up for day to day use. Keep the original safe.
I have back ups of all my money. I keep my real money hidden in shoe box under the water bed. Its a ***** to get too, but at least I know its safe there.