If both vehicles sit on one policy, the flagged record is rated against the whole policy. Splitting the vehicles onto separate policies sometimes costs less overall, and sometimes costs more. It has to be priced, not assumed.
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Multi-vehicle discounts cut the other way once a serious violation lands: the discount saves a percentage, while the surcharge applies to every rated vehicle. Whether splitting helps depends on the carrier, the vehicles, and the other drivers, which is why it is worth asking a producer to quote both structures rather than guessing. Two cautions. Splitting policies can forfeit multi-policy and multi-vehicle discounts that were doing real work, so the comparison has to be total household cost rather than the flagged driver cost alone. And a driver exclusion, which removes a person from coverage on a vehicle entirely, is a serious document: if the excluded driver ever operates that vehicle there is no coverage at all, and in a household where keys move around casually that is a real risk to weigh.