They're called keyed-alike locks and are sold in many big name hardware stores. It's something homeowners need to know.
"You might need three locks, but there may be 10 on the shelf, they are all the same key," said Ron Boddie with B&B Locksmiths.
Boddie says if you purchase locks from a big box store, there's reason for concern.
"Someone could be maybe watching what locks you're buying and find out where you're installing those locks," Boddie said.
Boddie says someone could purchase a lock with the same key and have access to your home.
"It leaves you vulnerable to someone else, maybe having a key that they shouldn't have," he said.
It's easy to spot locks that are keyed alike.
"Look right on the box and find a particular key number," Boddie said.
For example, locks by Schlage with the Number 10239; one key can open four locks. Kwikset is another popular brand that uses the same method with their packaging. One key can actually open six locks.
When we reached out to Home Depot to find out how many of their locks were keyed alike, they said, "We are not able to break out that information, and to contact the manufacturers."
If you do buy new locks and want added protection, Boddie has advice before installing them.
"The way to combat it is to have the locks re-keyed," he said.
To get your locks re-keyed, visit your local locksmith to have them do it for you. Or, just ask the store you're purchasing the locks from to re-key the lock to one you may already own. It's a process that should only take a few minutes.