fs.watch fired twice when I change the watched file

 fs.watch( 'example.xml', function ( curr, prev ) {
   // on file change we can read the new xml
   fs.readFile( 'example.xml','utf8', function ( err, data ) {
     if ( err ) throw err;
     console.dir(data);
     console.log('Done');
   });
 });

OUTPUT:

• some data
• Done X 1
• some data
• Done X 2

It is my usage fault or ..?