Example:
I build/install SoX myself, as provided Ubuntu package did not include additional audio format libraries that I might use and it's one of the packages I want latest version anyway.
Now I want to install eboard with Synaptic, and it wants to install SoX, but as mentioned SoX is already installed and working perfectly and I don't want to mess it with another install while I want to install eboard without building it from source.
This is example to problem I faced couple of times and thought to ask what Linux users do in such cases as I'm a new user.