The top compartment is designed to store a used pouch if you can’t immediately throw it away. Instead of throwing the pouch on the ground, store it in the top compartment until you find a trash can to dump the pouch in. It’s a small feature that customers enjoy using once they understand its purpose.
You can use the extra lid to help open the cans as well by sliding it through the indented middle section where the two parts of the can meet. You can also use it to store small items easily lost in pockets.