Mormons believe that the Urim and Thummim of Joseph Smith and the Book of Mormon were the functional equivalent of the Urim and Thummim mentioned in the Old Testament, but there is no indication that the Old Testament Urim and Thummin were used to translate documents.
The Urim and Thummim of Joseph Smith and the Book of Mormon were the functional equivalent of the Urim and Thummim mentioned in the Old Testament. This is what Mormons believe. The Old Testament Urim were used to translate documents. Thummin were used to translate documents. There is no indication this.