There was a case recently on one these watchdog type programmes. A car was stolen and the insurers refused to pay because the second key could not be provided. Their appeal was turned down. I don't think it would be wise to purchase any car with only one key.
That is a very good point, especially if the car is sold/bought locally. It's nice to think that we can trust someone BUT if they claim that they have lost the spare key and they really still have it would you be happy in the knowledge that they might still have access to your car?
