Random pagination using shortcode and WP-PageNavi

First of all, thanks for a great plugin…. it works great!

I am using WP-PageNavi with the [testimonialswidget_list].

It works perfectly fine, however when I select random order in the admin, it produces a random order much like the option suggests. However when I scroll onto the next page it shows testimonals that were also on the first page.

Is there a way to randomise it but not repeat the testimonials that have already appeared in the first/second pages etc?

If there is not – no worries – just thought I would ask.

http://wordpress.org/plugins/testimonials-widget/

Using latest version with WordPress 3.6