How to a Add Custom Meta Box for Multiple Post Type

[php]
add_action( ‘add_meta_boxes’, ‘myplugin_add_custom_box’ );

function myplugin_add_custom_box() {

add_meta_box( ‘myplugin_sectionid’, __( ‘My Post Section Title’, ‘myplugin_textdomain’ ), ‘myplugin_inner_custom_box’, ‘post’ );

add_meta_box( ‘myplugin_sectionid’, __( ‘My Post Section Title’, ‘myplugin_textdomain’ ), ‘myplugin_inner_custom_box’, ‘page’ );

}
[/php]

See: Stackexchange , Codex