It never happened twice

SCHOLARS SAY: “Virtually all scholars believe that Mark 16:9–20 was not originally part of the Gospel for the following reasons:

1. Some ancient manuscripts lack it and some of those that include it have a note that the text is disputed.
2. It is difficult to imagine why a copyist would omit it; it is much easier to imagine a copyist adding it.
3. Several early Christian writers appear to know copies of the Gospel of Mark that do not include Mark 16:9-20.
4. Most scholars find the style and theology of Mark 16:9–20 to differ substantially from the rest of the Gospel.
5. Matthew and Luke follow Mark pretty closely until they get to Mark 16:8, and then they go in very different directions, which suggests that they had copies of Mark that ended at Mark 16:8.
6. The transition between 16:8 and 16:9 is awkward: the subject shifts and the women in 16:1–8 are forgotten. Mary Magdalene is introduced to the audience as if they were unfamiliar with her despite the fact that she was mentioned just a few verses ago. (These problems not only suggest that Mark 16:9–20 was not original to Mark, but also that it wasn’t written afresh to end the text but rather was an already-extant writing added to fill a gap.)
7. There are over a dozen words included in Mark 16:9–20 that are not found elsewhere in Mark.
8. The presence of multiple different endings strongly suggests that Mark 16:9–20 was not present originally. It implies that more than one person (or group) found Mark 16:8 to be inadequate and decided to add to the ending.

–Julie M. Smith, BYU New Testament Commentary. [source]

ADDED TO MARK: “And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned. And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues; They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.” –Mark 16:15-18. [source]

ALSO PRESENT IN MORONI: “For behold, thus said Jesus Christ, the Son of God, unto his disciples who should tarry, yea, and also to all his disciples, in the hearing of the multitude: Go ye into all the world, and preach the gospel to every creature; And he that believeth and is baptized shall be saved, but he that believeth not shall be damned; And these signs shall follow them that believe—in my name shall they cast out devils; they shall speak with new tongues; they shall take up serpents; and if they drink any deadly thing it shall not hurt them; they shall lay hands on the sick and they shall recover;” –Moroni 9:22-24. [source]

COMMENTARY: One of the reasons the Book of Mormon was preserved by God was because He knew that some of the writings in the Bible would be perverted through the centuries, and the Book of Mormon would stand as a source of the real truth in cases where it had been corrupted and a confirmation of the truth in cases where God’s word had been transmitted correctly through the centuries. Right? So what are we to think when the Book of Mormon “confirms” something that we now know was never in the Bible originally? Was the Book of Mormon also corrupted by those same priests who corrupted the Bible? Or did one of the priests who changed the Bible act according to the Spirit of God and restore a lost truth that was not originally recorded? If the latter, then why wouldn’t that method have continued to work without the intervention of Joseph Smith? In my opinion it’s a series of questions worth pursuing. But what do I know? I’m just another apostate.