More than two Images?

Yes, you can create as many as you like. They just need unique ids for the same post type.

Is there an example of how to add more than a second image.

I tried like this.

if (class_exists('MultiPostThumbnails')) {
        new MultiPostThumbnails(
            array(
                'label' => 'Secondary Image',
                'id' => 'secondary-image',
                'label' => 'third Image',
                'id' => 'third-image',
                'label' => 'fourth Image',
                'id' => 'fourth-image',
                'post_type' => 'post'

            )
        );
    }

You just need to do this:

if (class_exists('MultiPostThumbnails')) {
        new MultiPostThumbnails(
            array(
                'label' => 'Second Image',
                'id' => 'second-image',
                'post_type' => 'post'

            )
        );
        new MultiPostThumbnails(
            array(
                'label' => 'Third Image',
                'id' => 'third-image',
                'post_type' => 'post'

            )
        );

    }

OK, this is an old post but let me share with you the following code for more than two featured images, e.g. let’s say 5:

if (class_exists('MultiPostThumbnails')) {
$i = 5;
while ($i <= 5){
new MultiPostThumbnails( array('label' => 'Extra Featured Image '.$i, 'id' => 'extra-image-'.$i, 'post_type' => 'post') );
$i++;
}
}

I hope this is helpful for someone!