Report php and Mysql with records of the same client

Good evening I hope and you can help me I have a query in mysql that displays the data in the following way

but I need the records to be this way

I'm doing the report with fpdf I have the following

$sql1 ="select a.estudiante_Carnet, b.PrimerNombre, b.PrimerApellido, a.Nota1
from notas a
inner join estudiante b
on a.estudiante_Carnet = b.Carnet
where b.grado_CodigoGrado='b3b'";

$res = mysqli_query($conexion,$sql1);
$row = mysqli_fetch_array($res);
$bandera = $row['b.Carnet'];


$pdf = new PDF();
//$pdf = new FPDF('P','mm',array(165,220));

$pdf->Addpage();
$pdf->AliasNbPages();


$pdf->SetFont('Arial','B',5);
    $pdf->Ln(10);

   $res2 = mysqli_query($conexion,$sql1);




    $pdf->Cell(10,10, "hola",1,1,'C',0);


while ($fila = $res2->fetch_array())  
{   

    if ( $bandera ==  $fila['b.Carnet'] ) {





    $bandera = $fila['b.Carnet'];

$pdf->Cell(10,10, $fila['PrimerNombre'],1,0,'C',0);         
   $pdf->Cell(10,10, $fila['Nota1'],1,0,'C',0);   
      $pdf->Ln();

  } 

  else { 

     ////////////////////////////////////////////////////////////////////   
    $pdf->Addpage();  


    $bandera = $fila['b.Carnet'];
      $pdf->Cell(10,10, $fila['PrimerNombre'],1,0,'C',0);  
   $pdf->Cell(10,10, $fila['Nota1'],1,0,'C',0);   
      $pdf->Ln();


}   
}

$pdf->Output();

?>