The rules regarding this vary from insurance company to insurance company. Apparently your insurance company applies a separate deductible to each loss. It is possible that the damage to your wife's vehicle could be claimed under your property damage liability coverage for which there should be no deductible, but not likely. Check with your claims adjuster to determine if this is possible.
On some auto policies, there is an exclusion under the Property Damage Liability coverage that excludes payment for damages to property owned by or in the custody of the insured. Therefore, your only option is to file a collision claim for each vehicle with a deductible for each.
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