Sorry, this is an off-topic question but I'm sure that Debian people know a lot about this issue.
I know some people who is trying to license their software as dual-license. Their intention is to be also able to release a propietary version of their software. However, I know that they have used a lot of LGPL software to build it, so in my opinion it is not possible. Do they have the right to release the software as dual-license? In my opinion to release a software as dual-license either all the code has to be developed by you or the license has to be compatible. Is this right?
Thank you