I use the Hudson Continuous Integration system to build my Symfony projects (will write a blog series about this in the next few days). For that I created a new task  for the Phing build system. Sebastian Bergamann wrote a Copy&Paste Detector for PHP some time ago (PHPCPD). This small tool scans PHP sourcecode for duplications. You can use the Task in a Phing build file as shown in the following sample:

<phpcpd haltonerror="false">

  <fileset dir="${builddir}" id="filestocpd">

    <include name="apps/**/*.php" />

    <include name="lib/de/**/*.php" />

    <include name="lib/task/**/*.php" />

    <include name="lib/services/**/*.php" />

    <include name="lib/form/**/*.php" />

    <include name="lib/model/**/*.php" />

  </fileset>

  <formatter type="pmd" outfile="reports/pmd-cpd.xml"/>

</phpcpd>

The CPD task is incorporatated in the current Phing trunk. If you want to use it you need to checkout the Version2.4.0 RC at the moment. The PEAR Installer version doesn’t contain the Task at the moment.

Maybe this is useful for you too. Stay tuned for more informations on Symfony and Continuous integration