Add To Wish List And Also Bought Clash

Hi

I have an issue on a store where when a customer adds a product to their wish list is also adds any products that have been bought with this item previously.

I can sort of understand if the customer in question had bought the items before but they haven't, other customers have.

Any ideas why this might be happening?

Thanks

Steve

At first try to disable all 3rd party modules and c heck the behaviour