Everything changes with the barrier gone
Dogs who are barking at each other through a fence are an unpredictable lot once the fence is no longer in the picture. Some of them improve their behavior if they are given the opportunity to meet and interact without a barrier, but others may cause real injury to one another. A rare few have no interest in any interaction other than barking at each other through the gate or fence, as is the case in the following video.
via Whisker Therapy