Does your car key have a twin?

KANSAS CITY, Mo. — Many of us wouldn't think of leaving our car unlocked on a city street or a parking lot or even in our own driveway. But that lock may not be as secure as we think. As one Johnson County mom discovered, someone else could have the exact same key.

Mom Christine learned that both her Hondas had the same key after 16-year-old son, Brad, grabbed the wrong set, but was still able to use it to unlock the car. The key he used to open the Honda Odyssey actually belongs to the family's Honda Accord.

"When I found out I was surprised because the cars were two years apart, bought at two different dealerships," Christine said. "It never occurred to me they would have the same key."

It's made her think twice about how safe she is when she locks her car.

"You think a key is a key and will keep everything safe," she said.

Locksmith Greg Brandt, owner of Brandt Locksmith in Kansas City, said its unusual, but not unheard of to find two cars with the same key.

"Each manufacture uses a certain number of tumblers and a certain number of depths of cut," Brandt said.

Like most car manufacturers, Honda has 3,500 different combinations, meaning eventually someone is going to end up with the same key as someone else, but twin keys showing up at the same house? Even Brandt acknowledged that was just weird.

It's not just car keys that have twins. Your house key is also not unique. In fact many of the locks you buy in hardware stores have identical keys. In fact, often a store will keep several locks on the shelf with identical keys for the convenience of customers who want multiple locks opened by the same key.

Locksmith Brandt said rekeying the lock won't make it any safer.

"If you want a higher degree of security you would have to go with a better grade of lock because rekeying it would just be changing it to another key and you wouldn't be gaining anything," Brandt said, who recommends dead bolts to those looking for a better lock.

So what are the chances thieves would be roaming your neighborhood with a huge set of keys hoping one of them might fit someone's door or house? It's highly unlikely. It's much easier to smash a car window or kick in a door, Brandt said.

In California, thieves are taking advantage of radio waves to break into Priuses. Thieves use a radio relay system to amplify the signal from a key inside someone's home so that they can break into the car in the driveway.

While there are multiple ways of opening a car with a key, it's far harder to steal one.

That's because each key has a unique chip that interacts with the ignition. So just because the key will open the door doesn't mean it will necessarily start the engine.