title: Sequelize.js save() result
body: <p>the code like this:</p>
  
  <pre><code>(function () {
      var tag = models.Tag.build({ create_time: new Date(), is_hot: '0', is_lock: '0', name: 'Nodejs' });
      tag.save();
      console.log(tag.dataValues);
      tag.name = "npm";
      tag.save();
      console.log(tag.dataValues);
      tag = models.Tag.build({ create_time: new Date(), is_hot: '0', is_lock: '0', name: 'webpack' });
      tag.save();
      console.log(tag.dataValues);
  })();
  </code></pre>
  
  <p>the result is: 
  <a href="https://i.stack.imgur.com/dCEqc.png" rel="noreferrer">the result</a></p>
  
  <p>in my first eys,the result maybe:</p>
  
  <pre><code>Executing (default): INSERT INTO `t_tag` (`id`,`name`,`create_time`,`is_hot`,`is_lock`,`is_delete`) VALUES (NULL,'Nodejs','2016-12-23 03:09:23','0','0','0');
  Executing (default): INSERT INTO `t_tag` (`id`,`name`,`create_time`,`is_hot`,`is_lock`,`is_delete`) VALUES (NULL,'npm','2016-12-23 03:09:23','0','0','0');
  Executing (default): INSERT INTO `t_tag` (`id`,`name`,`create_time`,`is_hot`,`is_lock`,`is_delete`) VALUES (NULL,'webpack','2016-12-23 03:09:26','0','0','0');
  </code></pre>
  
  <p>what causes that ?
  why the "npm" record insert double time?</p>