They wouldn't salvage the car if there was only minor front bumper damage, was the car still drivable when you got into the accident? I think it's probably a mistake on their side.
My imagination is your damage was $900 and they fixed it then started to rent the car again, then some idiot got into a major accident and it costs $9,000 and they pull up the accident record of the car and some idiot working there put it to your name.