Development of Creative Commons licenses

[Sigmascape1 AT cs.com]

Hello!

First question deals with the issue of dual licensing. I've read a lot of 
threads about it, but I need some help. Is it a common pratice for content, 
say a photograph, to be licensed under multiple CC licenses? Is it kind of 
like a Magnatunes situation, a kind of try before you buy thing?

My second question deals with selling content. I am looking into the 
possibility of releasing digital artwork I have created, and selling it on 
CDs. At the same time, I am going to make some of the same content available 
for free via my ibiblio account and on my website. Can anyone point me to 
other examples of people/companies selling CC'd content. My artwork is going 
to be licensed under the Creative Commons Attribution License.

Thanks!

Mitch