Discounts' duplicate & hide functionality creates hidden, duplicate versions of your store's products that can be offered through Upsell when certain conditions are met. Discounts does this to ensure that these items are not purchasable on their own, and that the customer must qualify for the discounted item(s) first.
Upsell then allows you to set the conditions for when this product will be offered. You can have the hidden discounted item(s) display when a specific product is added to the cart, when the customer is checking out with certain items, or when the customer's cart is within a defined price range.
Note: The duplicate & hide coding must be installed on your site in order for this functionality to work. If you create duplicate & hide products without the coding installation, these products will be visible and purchasable on your storefront.
Visit Create a Buy One Get One (BOGO) Offer for more information on how to set up this type of offer.