The only name I can recall for them was a "cross" or "safety" lever. The knickname was "suicide bar". If you keep your brakes properly adjusted, they will stop you fine.
They require much more handle movement before they engage which is a disadvantage, but if you watch well ahead of you and can see what traffic is doing, and adjust your speed accordingly, you shouldn't have any problems stopping.
There will be some members who will scream at you to get rid of them.
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ljbike