It’s likely that the plugin isn’t aware of the second price, so it’s not working its magic to change it. It might be worth asking the plugin author if it’s possible to apply their plugin to other prices on the page.
I contacted the support of the coin plugin and this was the response of the developer:
I checked your site, and It seems a problem relate to the “sticky add to cart” code. The “sticky add to cart” code is using the function product->get_price() instead of $product->get_price_html(). For variable products, the $product->get_price() function returns the value of the database without apply the round function.
This code issue is causing another problem: the “Load product price in the background” function can’t refresh the “sticky add to cart” price, because it does not include the PBoC classes.”