Yahweh invokes the law of witnesses to justify this second written text. The Book of Mormon, a second witness of Jesus Christ, fulfills this ancient law of legal testimony.
Even though Yahweh says that he speaks “the same words” to both nations, the level of Messianic knowledge in the two hemispheres suggests that he is not being literal here. Despite the differences, however, it is the same God and the same message, even though details vary with time and circumstances.
I read the description of two nations that “run together” as an allusion to the New World’s discovery by the Old World, a process that historically was more a violent collision than a confluence. The nations that were once separate and received separate revelations from God became known to each other, and so did their separate scriptures or revealed knowledge. The New World’s contribution to this “running together” is clearly the Book of Mormon. In addition to the Bible, the Old World has contributed such valuable texts as the Dead Sea Scrolls and the Nag Hammadi Library, even though they do not approach the doctrinal value of the Book of Mormon.