title: Android: query for albums gives duplicates
body: <p>I'm querying the contentresolver in order to list all the albums on the device. However I have losts of duplicate. Is it a problem of my query or of the android database? 
  Maybe is it because I'm getting albums from a songs' table?</p>
  
  <pre><code>String[] projection = {
                      MediaStore.Audio.Albums.ALBUM_ID,
                      MediaStore.Audio.Albums.ALBUM,
                      MediaStore.Audio.Albums.ARTIST
              };
  
              String selection = null;
  
              Cursor cursor = context.getContentResolver().query(
                      MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
                      projection,
                      selection,
                      null,
                      null);
  </code></pre>
  
  <p>Thank you </p>