title: Why does macports list multiple installed ports of the same version, and how do I fix it?
body: <p>Specifically, the command:</p>
  
  <pre><code>sudo port list installed
  </code></pre>
  
  <p>Shows doubles of packages, like this:</p>
  
  <pre><code>apache2                        @2.2.21         www/apache2
  apache2                        @2.2.21         www/apache2
  ...
  ncurses                        @5.9            devel/ncurses
  ncurses                        @5.9            devel/ncurses
  php5-iconv                     @5.3.8          php/php5-iconv
  php5-iconv                     @5.3.8          php/php5-iconv
  php5-intl                      @5.3.8          php/php5-intl
  php5-intl                      @5.3.8          php/php5-intl
  ...
  </code></pre>
  
  <p>Why is this?</p>
  
  <p>How did it happen and how do I fix it?</p>