Two kids of the goats were brought to the High Priest, and lots were cast to see which of the two would be killed as a sacrifice for the sins of the people (Lev. 16:15-19). After the blood sacrifice was completed, the High Priest laid his hands on the other animal's head, he confessed "over him, all the iniquities of the children of Israel," and then it was driven from the camp into the wilderness (Lev. 16:20-28).
The second animal has been called the "scape goat" in the KJV of the Bible, as the translation for the Hebrew עֲזָאזֵל (`aza'zel). Most of us are familiar with the term "scape goat," but very few know what the Hebrew word means. Breaking it down (although I could find no support for this), I believe it means "to be gone from the sight and presence of God." God was present within the camp; the "scapegoat" was literally taken from the camp of Israel into the wilderness (Lev. 16:21-22). To me, it sounds a great deal like what God told us through Isaiah, who wrote, "I, [even] I, [am] He that blotteth out thy transgressions for Mine own sake, and will not remember thy sins" (Isa. 43:25 - see also Jer. 50:20; Mic. 7:18; Heb. 8:12; 10:17). The "blotting out" was the blood of the sacrifice, and the "forgetting" was memory of the sins being removed by the "scape goat."
There is another possible parallel for this Feast of Israel. Could the slain animal be a picture of "the Lamb of God" who shed His blood for the sins of the world?" (Jn. 1:29, 36; 1 Jn. 2:2; etc.). If so, the other animal could be a picture of Satan bringing up all our sins "from the books" at the Great White Throne Judgment, where, I believe, all that a man has done in this life are recorded (Rev. 20:11-13). This makes sense, in that, the Hebrew word aza'zel has been interpreted to represent Satan by many Hebrew scholars. Since Satan is our adversary, the one who accuses the brethren before God, does it not seem logical that the "books" being opened were opened by him to charge us before God? Job 31:35 says, "Oh that one would hear me! behold, my desire [is, that] the Almighty would answer me, and [that] mine adversary had written a book." And in 1 Peter 5:8, we read "Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour."
Regardless, there is really only one book that matters: the "Lamb's Book of Life" (Phil. 4:3; Rev. 13:8; 17:8; 20:12; 21:27)! Everyone's name is in "the books," but only the redeemed are in the "Lamb's Book of Life."
Just as one needs two births, one also must be recorded in two books!