foreach loop duplicates values php sql

Question

Why this double foreach loop duplicates values

 foreach($_POST['studentpoints'] as $value) {
        foreach($_POST['studentids'] as $valor) {
            $stmt->bindParam(':studentid', $studentids);
            $stmt->bindParam(':studentpoints', $points);
            $studentids = $valor; 
            $points = $value;
            $stmt->execute();
        }

This code don't duplicate the values, but only read the first id for students

foreach($_POST['studentpoints'] as $value) { 
        foreach($_POST['studentids'] as $valor) {
           $studentids = $valor;
        }

   $stmt->bindParam(':studentid', $studentids);
            $stmt->bindParam(':studentpoints', $points);
            $studentids = $valor; 
            $points = $value;
            $stmt->execute();

}

Table with data from database

<?php foreach($rowstudents as $row): ?>
  <tr>
    <th><input type="hidden" name="studentids[]" value="<?php echo ' ' . htmlentities($row['studentid'], ENT_QUOTES, 'UTF-8') . ' ';?>" />
    <?php echo '' . htmlentities($row['studentid'], ENT_QUOTES, 'UTF-8') . '';?></th>  
    <th><?php echo '' . htmlentities($row['fname'], ENT_QUOTES, 'UTF-8') . '';?></th>
    <th><?php echo '' . htmlentities($row['lname'], ENT_QUOTES, 'UTF-8') . '';?></th> 
    <th><input type="text" name="studentpoints[]" value="<?php echo '' . htmlentities($row['studentpoints'], ENT_QUOTES, 'UTF-8') . '' ?>"></th>
  </tr>
<?php endforeach; ?>
</table>

Answer 1

You are using a for each loop twice. Apart from that it doesn't seem there is any problem

Answer 2

   for ($i=0; $i<count($_POST['studentpoints']); $i++) {
           $studentids = $_POST['studentid'][$i]; 
           $points = $_POST['studentpoints'][$i];

           $stmt->bindParam(':studentid', $studentids);
           $stmt->bindParam(':studentpoints', $points);
           $stmt->execute();

   }