How to create a clone role in wordpress

How to create new role with same capabilities of existing role.
Eg: I would like to create a new role with same capabilities of administrator or editor and so on..

Try this… This should work.

<?php
add_action('init', 'cloneRole');

function cloneRole()
{
    global $wp_roles;
    if ( ! isset( $wp_roles ) )
        $wp_roles = new WP_Roles();

    $adm = $wp_roles->get_role('administrator');
    //Adding a 'new_role' with all admin caps
    $wp_roles->add_role('new_role', 'My Custom Role', $adm->capabilities);
}
?>

Check it.