spare key

I put the spare keys in there too, except the one for the office.

They used to keep a spare key under the mat.

They'd done this often enough to have a spare key on hand.

The next move was to check all the likely places where a spare key might be hidden.

Under the third one from the left, he knew, was the spare key.

"Anyone could have taken the spare key to the command post."

Now, if you'll just give me a spare key to the apartment.

And so she'd put a spare key under the rock.

I'll need a spare key to his room, of course.

He knows where I like to hide my spare key.