Table multiplying the data

Well, I've had this problem for some time and I would like the help of you, I have 3 tables that would be sale, vendaproduto, vendaservico. and I insert the sales table items into the other two tables with the following code:

       mysql_query("INSERT INTO vendaproduto (id_venda, produtos)
SELECT  venda.id_venda, venda.produtos
FROM venda")or die(mysql_error());

    mysql_query("INSERT INTO vendaservico ( id_venda, servicos)
SELECT  venda.id_venda, venda.servicos
FROM venda")or die(mysql_error());

As soon as I enter the first line everything is ok, but when I enter the second line, in the two tables (vendaproduct, saleservico) already doubles the number of lines and with each new record the line number doubles, someone can Help me with that?

code all:

<?php
ini_set('default_charset','UTF-8');

if(isset($_POST['send'])){
    $venda = $_POST['num_venda'];
    $data = $_POST['data_venda'];
    $placa = $_POST['placa'];
    $km = $_POST['km'];
    $produtos = $_POST['produtos'];
    $servicos = $_POST['servicos'];


    include ('banco.php');


    mysql_query("INSERT INTO venda(id_venda, num_venda, data_venda, placa, km, produtos, servicos)
            values(
                NULL,
                '{$venda}',
                '{$data}',
                '{$placa}',
                '{$km}',
                '{$produtos}',
                '{$servicos}'

                            )
            ");
    mysql_query("INSERT INTO vendaproduto (id_venda, produtos)
SELECT  venda.id_venda, venda.produtos
FROM venda")or die(mysql_error());



    mysql_query("INSERT INTO vendaservico ( id_venda, servicos)
SELECT  venda.id_venda, venda.servicos
FROM venda")or die(mysql_error());

}

header("location:lista.php");
?>

Tables: