Actually, the government already has this right.
Firstly, you have to send a copy of your work to the
Libary of Congress to achieve a defensible copyright status.
Secondly, Congress enacted a copyright law which allows an archive
to "save the bits" that is, make an archival copy of any
document for safe-keeping. This is particularly true for
volatile magnetic disk documents and somewhat for fragile CD's.
My local library does it routinely, and actually bought a CD
duplicator for the purpose. As for the LoC, it is so
bogged down with traffic that requiring their attention to
this as a duty might be a good idea. One copy in D.C. and
another in Fort Knox (on Kodak gold CD's, I suppose).