Thank you for contacting Product Support. No it is only made to hold one 12X13 insert at one time. You should order two inserts so that when you are using one the other can be getting cold in your freezer and will be ready when the one in your wrap gets warm.
1 Being overweight: Excess body mass can decrease blood circulation, causing fluid to build up in the feet, legs, and ankles.  Standing or sitting for long periods: When the muscles are inactive, they canât pump body fluids back up toward the heart. The retention of water and blood can cause swelling in the legs.
Causes of Swelling. Swelling in the feet is typically caused by a buildup of fluids. Also called edema, swelling can be brought on by tight, uncomfortable shoes. Diabetes or a medical condition that causes fluid retention may also make you vulnerable to foot swelling.