I have always looked at Mormonism to be unique and had trouble believing its claim to be a restoration of origianal Christianity. However some 30+ years after leaving the LDS church I came accross more and more unique deemed features that on closer investigation are not really that novel at all.
(1) Theogony. For example Mormons believe in a succession of Gods, that makes then unique among the Abrahamic religions. Mormonism deviates so much from the core beliefs of all Abrahamic faiths that one could argue that it isn't a sect anymore, but a religion outright. But Theogony was well established among the Greek and hence is not original. https://en.wikipedia.org/wiki/Theogony
(2) Polygamy. It is not unique in the Abrahamic tradition, but Mormon Polygamy is or has been a requirement for Salvation (called Exaltation), which is only available to temple worthy members (LDS). LDS still believe in Polygamy, but won't practice it on earth.
(3) Masonic Temple Endowments. They are the foundation of Mormonisms destinct salvific beliefs. Masonry was seen as a evil in the Book of Mormon (secret societies), but there where times when masonic and evangelical beliefs where seen compatible and part of evangelical missionary training at Dartmouth College (US). Check out ....
The Lucy Code &facebook https://www.facebook.com/pg/mormontruth/posts/
The original King James Bible masonically illustrated: https://www.cuttingedge.org/news/k1002.cfm
(4) Eternal Marriage. Not unique, ask Swedenborg. https://swedenborg.com/spiritual-marriage/