What type of combo front door lock, automatically unlocks by just turning the knob from the inside?

Question

This is a little confusing. If I don't explain this clearly, please let me know so I can add details.

I recently moved into a new home. There is a combo lock on the front door that consists of two locks(top and bottom) encased in a silver rectangular cover. There is one keyhole on the outside of front door, and one key unlocks both locks at one time.

Ok, from the inside I must turn the latch on the top lock, to the right, for it to lock the door. For the bottom lock, I must push the button in, and turn it to the right, for it to lock.

Now here is what's weird, when both the top and bottom lock are turned to the right and locked from the inside, so no one can get in from the outside, if I turn the knob to the left, without unlocking either lock, both automatically release and I can open the door.

Is this supposed to happen? What type of lock is this, and is it secure? I've never had a lock like this. Thanks

I'm wondering if it's broken, stripped, or something. Thanks

Also, if the lock is secure, what is the name of this combo lock?

Answer 1

The push button type locks always unlock from the inside when turned. Since the key from the outside does the same thing as turning the doorknob, (releasing the push button lock) we know that nothing is broken. The deadbolt part of the lock is connected to the key part and operates as it is supposed to, nothing broken there. I would not worry about it, in fact I would like to have one.

Answer 2

Yes that makes it possible to have a deadbolt type of lock (harder to break into the house), but to prevent the possibilty of being trapped inside the house by the same deadbolt, it unlocks when the knob is turned from the inside.