Your main problem is that the is_page() conditional will not return true if it is included inside or after the loop.
Your other issue which is not necessarily related to the issue at hand is the way you are including your sidebars. WordPress comes with a handy little function called get_sidebar(). If you have more than one sidebar you can pass a parameter to the function that lets it know what sidebar you want.
You need to name your sidebars sidebar-{sidebar_name}.php. So if you wanted to include sidebar1 you would name your file sidebar-sidebar1.php and to include it is simply get_sidebar( 'sidebar1' )
To solve your is_page() problem you can either call wp_reset_query() after your loop or assign the conditional return boolean to a variable before the loop then use it when including your sidebar.
//Somewhere before the loop
$page_var = is_page( 'blog' ) ? true : false;
//loop stuff
if ( $page_var ) {
get_sidebar( 'sidebar1' );
} else { get_sidebar( 'sidebar2' ); }