Double front door lock

[Mosh]

If the front door of a small block of flats (converted house) has two thumb-turn locks, as in the picture, is that a problem? 

[AnthonyB]

Ideally there should only be one fastening, however thumb turns are commonly used in housing.

The yale type lock is more of a problem as it looks like the type that can be key locked from the inside.

[Mosh]

Thank you, Anthony.