query_posts different amount of posts per page [duplicate]

Try this code here

<?php 
$paged = get_query_var('paged') ? get_query_var('paged') : 1;
if($paged == 1){
    $posts_per_page = 100;  
}else{
    $posts_per_page = 300;
}
query_posts( array(
     'posts_per_page' => $posts_per_page,
     'post_type' => array( 'regularproducts', 'wpsc-product' ),
     'paged' => $paged,
));
?>