Insured on 2 cars. What happens to my no claims bonus?

I am now insured on 2 cars as the main driver. My car I am the registered owner and keeper and have 12 years no claims bonus. On the second car I am not the legal owner or registered keeper and as my 12 years are on the other car I have 0 no claims on this one.

The insurers are different.

What will happen to my 12 years no claims on my car if I have an accident in the car that has 0?