It is good. Suppose a visitor visited your website. So when he views a product, the facebook pixel counts an event and sends that event to your Facebook event manager. When you set up a server side or conversion API, when a visitor clicks a product view_content two events will be added to your event manager. Because one browser site has moved to another server site or conversion API site. These two need to be duplicated to convert them into one so that an event shows up in your Facebook Event Manager.

If it is duplicated then it is working fine.