Ecoe sua seleção final fora do loop.
while ($row = mysqli_fetch_array($r))
{
echo '<option value="'.$row['employee_name'] . '>"'.$row['employee_name'] .'</option>';
}
echo "</select>";
while ($row = mysqli_fetch_array($r))
{
echo '<option value="'.$row['employee_name'] . '>"'.$row['employee_name'] .'</option>';
}
echo "</select>";