Datetime Attribute - bug?

Do I miss something or is there a bug??

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    <h1>Tournaments</h1>
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    <h2>Mortal Combat Tournament Survey Results</h2>
    
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    <p>Thank you to everyone for responding to Master Camper Cat's survey. The best day to host the vaunted Mortal Combat tournament is Thursday, September 15<sup>th</sup>. May the best ninja win!</p>
    
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      <h3>Comments:</h3>
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        <p>Posted by: Sub-Zero on <time datetime="2016-08-13T20:01Z">August 13<sup>th</sup></time></p>
        <p>Johnny Cage better be there, I'll finish him!</p>
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        <p>Posted by: Doge on <time datetime="2016-08-15T08:12Z">August 15<sup>th</sup></time></p>
        <p>Wow, much combat, so mortal.</p>
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        <p>Posted by: The Grim Reaper on <time datetime="2016-08-16T00:00Z">August 16<sup>th</sup></time></p>
        <p>Looks like I'll be busy that day.</p>
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      <p>Posted by: The Grim Reaper on <time datetime="2016-09-15">"Thursday, September 15<sup>th</sup></time>
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  </article>
  <footer>&copy; 2016 Camper Cat</footer>
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