Schlage Securekey
The double-cylinder DB was an old-style Schlage lock with covered screw holes.
It took a while to take it out though. The replacement lock was purchased by the customer a while back but couldn't be installed because they didn't know how to remove the current lock.
There replacement lock has a Schlage Securekey lock which I didn't know at the time. It has a plus sign on the face of the plug.
It uses a blue reset key and is a re-keyable lock. This is the first time I ran into it on the field.
Another locksmith said they don't make these anymore because they've had problems with it. Does anyone else have an opinion on these type of locks. They are suppose to be bump-proof and more pick-resistance.