title: liquibase - 1 change sets had duplicate identifiers
body: <p>Liquibase tells me :</p>
  
  <pre><code>1 change sets had duplicate identifiers
            classpath:config/liquibase/changelog/20160610094343_changelog.xml::1465551835616-1::techvalley (generated)
  </code></pre>
  
  <p>I have looked for id <strong>1465551835616-1</strong> in the code of my app, it's only in the file 20160610094343_changelog.xml (and only once).  I don't understand where this error can come from.</p>