Yes, every time you update a post using wp_update_post() it generates a revision in addition to the one created when it is updated in the admin.
In order to prevent this you must remove the built in WP filter to save a revision
remove_filter('post_updated', 'wp_save_post_revision', 10);
and then add it back again
add_action('post_updated', 'wp_save_post_revision', 10);
It can get complicated depending on what revision you want to prevent. The one created during the normal update process or the one that is created when you manually call wp_update_post()
