CA Ins Code Section 11629.78

(a)

An insured under the program shall not purchase automobile liability insurance coverage that is in addition to the liability coverage provided by the low-cost policy. However, the insured may purchase any other additional type of automobile insurance coverage, such as uninsured motorist coverage or collision coverage outside the plan.

(b)

An insured under the program shall not purchase or maintain any automobile liability insurance coverage other than a low-cost policy for any additional vehicles in the insured’s household.

(c)

No more than two low-cost policies per person are permitted.