title: CPACK .deb installer backup previous installed version
body: <p>Is there a way to backup the previous installed version of a .deb package generated by cpack? 
  I have a project that i need to deploy manually on multiple equipments in a live production site. To minimize error and time spent deploying, i would like to use cpack and a .deb generator to create a package. 
  But i also want to keep the previous installed version, and config files for fast roll-back.</p>
  
  <p>I have already have a package with can be successfully installed with it's configuration files. Contained in a folder with the version as a name. But when I install the new version it automatically removes the older version. Is there a way to stop the installer from doing this?</p>