This is something I see in houses every once in a while. The deadbolt is keyed inside the house and lacks the normal handle to lock and unlock. Most people who have these installed believe that it is a security feature. This door has a window next to the deadbolt and the thinking is that if the window is broken by an intruder they wouldn't be able to open the deadbolt if it requires a key.
While this is possibly true, if an intruder or burglar really wants to get in there are other ways they could do it (other windows, sliding door, kicking the door in). In reality, most people with a double keyed deadbolt leave a key in the lock anyway.
The real issue with a double keyed deadbolt is the danger it poses to occupants of the house. Code requires that any means of egress (exit) during an emergency to be able to be operated without any special tools, procedures or knowledge. If there is a fire inside the house that is the day that someone would have taken the key out of the lock. You need to make things easy on yourself during an emergency - adrenaline and panic do not necessarily lead to rational thought and problem solving. If the means of exiting your house requires a key from the inside you are putting all the occupants at risk of injury or even death.
This deadbolt needs to be replaced with a standard lockset with a handle on the inside. This is a fairly simple fix that can be done by most homeowners.
Brian Jovag, owner of Jovag Home Inspection.