Combine Karo syrup and brown sugar in a large microwave safe bowl. Microwave on HIGH for 3 minutes or until you see bubbles to show it has just begun to boil.
Add peanut butter and stir. Add Rice Krispies and mix. Press into a 9 x 13 pan.
Place both bags of chip in a microwave safe bowl. Mix the chips together a little bit. Microwave on HIGH 1 minute at a time until they are melted stirring after each minute. Spread over Rice Krispie mixture.