UPVC French Doors Security.

[Omits]

I have French Doors. The main door locks OK. The second door (usually closed) has a lock and key but does not lock. Even with the main door locked, although it keeps the second door from opening, the handle on the second door can be pushed down. So it has a mechanism to keep the door in place but cannot actually be locked (the main door keeps it closed when shut and locked. Is this right or should the second door lock independently? Thanks.