As far as your car hire excess insurance policy is concerned it makes no difference if you drop your hire car off at the same car rental station you collected it from, or whether it was a one-way car hire. The excess policy covers you (to reimburse you should you have to pay out for damage) and not the car.
You do not need to have the car checked at your original car hire office, as long as it is returned to an authorised office from the company you have rented it from.
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If you have any queries do call a member of the MoneyMaxim car hire insurance team.