循环结果执行两次

我用PHP创建了一个简单的网站，用户可以在其中提交博客，其他用户（已登录）可以在上面发表评论。我在每个博客下方制作了一个名为"评论"的链接，单击该链接时将显示/隐藏与特定博客相关的所有评论（如果用户已登录，它将显示一个表单字段，他们可以在其中提交新评论）。所以基本上每个博客都会有多个评论。我为此做了两个不同的代码，但它们都有相同的问题，每个评论出现两次（其他一切正常）。谁能指出为什么？

mysql_select_db ("ooze"); 
$result = mysql_query ("select * from blog") or die(mysql_error()); 
$i = 1;   
 while($row = mysql_fetch_array($result)) 
 { 
  echo "<h1>$row[title]</h1>"; 
  echo "<p class ='second'>$row[blog_content]</p> ";  
  echo "<p class='meta'>Posted by .... &nbsp;&bull;&nbsp; $row[date] &nbsp;&bull;&nbsp; <a href='#' onclick='"toggle_visibility('something$i'); return false'">Comments</a><div id='something$i' style='display: none;'>";     
  $i++; 
  $a = $row["ID"];
  $result2 = mysql_query ("select * from blog, blogcomment where $a=blogID") or die(mysql_error()); 
    while($sub = mysql_fetch_array($result2)) 
    { 
     echo "<p class='third' >$sub[commentdate] &nbsp;&bull;&nbsp; $sub[username]</p><p>said:</p> <p>$sub[comment]</p>"; 
     } 
 if ( isset ($_SESSION["gatekeeper"])) 
 { 
    echo '<form method="post" name="result_'.$row["ID"].'" action="postcomment.php"><input name="ID" type = "hidden" value = "'.$row["ID"].'" /><input name="comment" id="comment" type="text" style="margin-left:20px;"/><input type="submit" value="Add comment" /></form>'; 
 }  
 else 
 {  
    echo '<p class="third"><a href="register.html">Signup </a>to post a comment</p>'; 
 } 
echo "</div>"; 
}
mysql_close($conn); 

内 loop://的第二个版本

if ( isset ($_SESSION["gatekeeper"])) 
{
  while($sub = mysql_fetch_array($result2)) 
  { 
    echo "<p class='third' >$sub[commentdate] &nbsp;&bull;&nbsp; $sub[username] said:</p> <p>$sub[comment]</p>"; 
   }
echo '<form method="post" name="result_'.$row["ID"].'" action="postcomment.php"><input name="ID" type = "hidden" value = "'.$row["ID"].'" /><input name="comment" id="comment" type="text" style="margin-left:20px;"/><input type="submit" value="Add comment" /></form>'; 
}  
else 
{
  while($sub = mysql_fetch_array($result2)) 
  { 
    echo "<p class='third' >$sub[commentdate] &nbsp;&bull;&nbsp; $sub[username] said:</p> <p>$sub[comment]</p>"; 
  }
echo '<p class="third"><a href="register.html">Signup </a>to post a comment</p>'; 
 } 
echo "</div>"; 
} 
mysql_close($conn);