[phkahler]

One can contractually agree to make some else the exclusive source for something while retaining the copyright. In which case, if you then offer it to someone else then that "exclusive" party can sue you for breach of contract. Of course this has nothing to do with any of the open source or CC licenses.

[delinka]

Now we're off into contract law instead of copyright law.

[jrochkind1]

Licenses are contracts. That's what a license is.