It's not possible to select 2 additional insurances. Only Plus or Super can be added to the mandatory insurance.
If you want to rent a car for just 1 day, that is also possible. The price will show up differently on your order, but 1 day rental has a fixed price. See prices below: 1 day rental: - Small cars: $75,- Fixed price (All Inclusive). - Pickup trucks and SUV's: $90,- Fixed price (All Inclusive).
You can read the term and conditions HERE.