Deductible—Per Vehicle or Per Loss?

Our personal auto policy insured was towing his own vehicle behind his own motor home. During the course of the trip, the towing bar broke and the auto crashed into the back of the motor home. Our question involves the deductible amount for this loss: does the $500 collision deductible apply to the loss or to each vehicle? We (the insurance company) say it applies to each vehicle while the agent contends that only one deductible would apply. The agent bases his contention on communication with others in the industry and also (as a former police officer) on the fact that, had the driver been arrested for speeding, he would have received only one speeding ticket although two vehicles were traveling down the highway. Your opinion?

Ohio Subscriber