The double screws just seemed like such a good professional approach.They had double screws on every connection except the earth bar, didn’t they.
Certainly reduced the chances of a connection problem more than some of today’s lovely jubblies.
In the past, if extending a CPC with a choc-block I would have the two conductors passing each other inside so both of the choc's screws clamped both conductors.
The likes of spring-loaded Wagos ought to avoid the reliability issues of correct initial torque and loosening due to vibration or thermal cycling though.