When they say it here it is metaphorical, meaning that Christ and God have the same interests and basically goals. Do not quote me on this, I'm not well studied on this subject, but I have looked a bit into this. Also keep in mind, that in our Book of Mormon, it explicitly says that there are 3 divine beings, not one with three aspects (also don't quote me on that I don't really know what other people believe that well as I'm only 13) many times, and that is the book of doctrine that our religion is primarily based on.
I also have an answer to this. The Book of Mormon is another testament of Jesus Christ, but it follows events in the Americas while the Bible takes place in the Middle East. Keep in mind, Joseph Smith found the golden plates that led to the book of Mormon only about 50 years after the U.S. was made a country, so also about 50 years after the North America were majorly colonized.
I will try my best to answer any questions about The Church of Jesus Christ of Latter Day Saints as I can. While I am only 13, I am more well versed in this topic that most 20 year olds in the LDS church, and am happy to help people understand my religion, But honestly, Immortal platypus seems more educated about this than I am.