Working from my own exposure here in the USA, dual trip coils used to be rare outside of HV transmission equipment. In that application, with primary and backup protection, two trip paths and cross-tripping schemes were used.
I am not speaking of the undervoltage trip device employed by some manufacturers, used to open breakers in motor service, etc. I am talking about a separate trip coil that when energized will open the breaker.
In heavy industry, I saw very few companies specify dual trip coils, even in critical equipment installations. If you're going to use a second trip coil, what factors are you employing to make it worthwhile? Separate trip power source? Protective device completely isolated from the primary trip device?
It is interesting to note that in the majority of cases where I have investigated breakers failing to trip, the cause of the failure was mechanical, and a second trip coil usually acts on the same mechanical latch as the first trip coil.
old field guy