Double Waiting list buttons on product page

I am using the free version of YITH Waiting list in the Merchandiser Theme of getbowtied. My site is in Dutch. I also installed the YITH Wishlist plugin. I have a bug to report:

On the product page of an out of stock product, I see the Dutch Waiting List text & button (=OK), underneath the Wishlist button & text (= OK) and underneath this there is an English Waiting list text and button (which should be removed). How do I fix this? Or is it a bug within the plugin?

The page I need help with: [log in to see the link]