To me it sounds like this is one of the reasons for making backup copies in the first place!
I don't think they are "pirated"/"illegal" at all, certainly not in any moral or ethical sense whatsoever. And i'm positive that in my country, they would not be considered "pirated".
However, I take it you are writing from the U.S., and i have no idea what sort of laws you have. My understanding is that ethics/common sense do not necessarily apply. I would ask a lawyer to settle the issue, if you really care that much about settling the argument. Industry guidelines are not likely to give you an accurate idea of the laws involved, in my experience (and speaking as the husband of a lawyer).