apt takes my packages back to normal version

[Andrea Ratto <andrearatto_liste@xxxxxxxx>]

I am using the versioning convention suggested in the ppa quick start
guide, but some of my package get 'upgraded' back to the version in the
official repo by apt. 

Here is an example:

andrea@andrea-laptop:~$ LANG='' apt-cache policy libccid
libccid:
  Installed: 1.3.0-2ubuntu1~ppa1
  Candidate: 1.3.0-2ubuntu1
  Version table:
     1.3.0-2ubuntu1 0
        500 http://archive.ubuntu.com gutsy/universe Packages
 *** 1.3.0-2ubuntu1~ppa1 0
        500 http://ppa.launchpad.net gutsy/main Packages
        100 /var/lib/dpkg/status

I am just recompiling the official package with different options or
small patches, do I have to change the ubuntuX version?
Thanks.