Generally, they just copy them, the stuff you see remaining is what was necessary to build the program, and can be deleted after you finished compiling the software.
Just type 'kopete' in the CLI, and I'm sure you'll see Kopete, in fact, did install.
You might, however, want to look into
Checkinstall, a nice little app that turns your source built programs into packages, for easy management.
Hope I helped
