Test for the forms id conflict bug

testform.php

<?php

require_once(__DIR__ . '/config.php');
require_once($CFG->libdir.'/formslib.php');

require_login();
$PAGE->set_url(new moodle_url('/testform.php'));
$PAGE->set_context(context_system::instance());

class testform extends moodleform {
    public function definition()
    {
        $mform = $this->_form;
        $mform->addElement('course', 'courseid');
        $this->add_action_buttons();
    }
}

$form1 = new testform(null, null, 'post', '', ['data-random-ids' => 1]);
$form2 = new testform(null, null, 'post', '', ['data-random-ids' => 1]);

echo $OUTPUT->header();
$form1->display();
$form2->display();
echo $OUTPUT->footer();