Note Submitter: Marques Johansson
Despite the documentation for 'type', you can specify multiple types by doing:
$test = filter_input(INPUT_GET | INPUT_POST, 'test');
This was tested in 5.2.3.
When both are set it appears to return the value defined first by variables_order (php.ini).
This trick does not seem to work in filter_input_array though. Neither function supports INPUT_REQUEST at the moment.