A twin 12.2 litre 230 bar with an 11 litre 207 bar deep deco mix and a 5.5 litre 207 bar shallow deco gas will carry 10 kilograms of gas, and while it is unlikely that all will be used on the dive, it is possible, and the diver should be able to remain at the correct depth for decompression until all the gas is used up.