I forgot something about copyrights.
JTattoo is multiple licensed, but only GPLv2 and v3 can be used for free, it's necessary to pay to use the other licenses. Do I list those licenses as well in debian/copyright?
Most files in cmake/Modules/ contained only a pointer to the full copyright text, and asked to replace that by the full license in Copyright.txt if distributed outside of CMake, which I did in the upstream source code.
However, I don't know what to do to the "Copyright ..." lines. Leave them intact (what I did), merge them with the Copyright lines from the Copyright.txt, or replace them?