Double sided blister packaging is typically used to show the front as well as the back of the product. Also double sided blisters are used in those cases where the weight or depth of the product is an important factor. By positioning the weight of the product in the center the packaging will hang perfectly straight in the shelf. Double sided packages are sometimes used to avoid very deep single blisters.
Full plastic front and back blisters with an insert card in between are used to make double sided packaging, but also a front and back card can be used in combination with a front and back blister trapped in between.