Changes to Duplicated Style Class affects the original

Hello
I am having an issue in composer pro
i duplicated the default list item style class to create a User_list_item and the i modified it with the component template editor to my needs, then i needed to make a product_list_item so i duplicated the User_list_item and changed the icons inside added some text only to find that the User_list_item also got affected and became like the Product_list_item.
so please if anyone knows how to fix this please help because i need to make more custom list items and i dont want to keep dublicating the default list item and doing the same work multiple time.
Thank you and i am sorry for my bad English.