If you’re seeing two sets of images when you activate WooThumbs, this means your theme has hardcoded the display of images, where it should be using a WooCommerce hook. In other words, it is overriding what we want WooThumbs to do.
The first thing to do is to check your theme folder and find the
woocommerce/content-single-product.php file (you might need a developer to help you with this).
If you see the images in there, simply remove them, but leave the
woocommerce_before_single_product_summary action in place.
Also, make sure you’re not using YITH Image Zoom, as this will also add a set of images.