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.
This is important to note because new swelling in just one foot can be caused by a blood clot in the leg or by an injury to the foot or ankle. When both feet are swollen, the cause is almost always fluid retention in the legs.