> If I understood clearly, following modifications of dual-licensed code > should also be dual-licensed, wouldn't they?
should, or must? must. Another argument has popped up elsewhere (by some poster, on kerneltrap.org), pointing out that the GPL itself may also require dual-licensed software to remain dual-licensed. The implication is that a recipient read both licenses, and then CHOSE the GPL, the GPL would then them to pass on the choice they had to whoever they distributed it to. Yes, you get to see me quote a paragraph from the GPL. Just this once. Never again. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. More can be found at kerneltrap.