The two goats formed a single sin-offering, Leviticus 16:5. To bring out the meaning of the sacrifice it was necessary that the act of a living being should be performed after death. See Leviticus 16:22 note. As this could not possibly be visibly set forth with a single victim, two were employed, as in the case of the birds in the rite for the healed leper Leviticus 14:4-6.
For the scapegoat - Rather, for Azazel. The word occurs nowhere else in the Old Testament but in this chapter, and is probably derived from a root in use in Arabic, but not in Hebrew, signifying to “remove”, or “to separate”.
Azazel is the pre-Mosaic name of an evil personal being placed in opposition to Yahweh. Each goat, having been presented to Yahweh before the lots were cast, stood in a sacrificial relation to Him. The casting of lots was an appeal to the decision of Yahweh (compare Joshua 7:16-17; Joshua 14:2; Proverbs 16:33; Acts 1:26, etc.); it was therefore His act to choose one of the goats for His service in the way of ordinary sacrifice, the other for His service in carrying off the sins to Azazel (see the note at Leviticus 16:22). By this exppressive outward sign the sins were sent back to the author of sin himself, “the entirely separate one,” who was banished from the realm of grace.
The goat itself did not lose the sacred character with which it had been endued in being presented before Yahweh. It was, as much as the slain goat, a figure of Him who bore our griefs and carried our sorrows, on whom the Lord laid the iniquity of us all Isaiah 53:4, Isaiah 53:6, that we might become a sanctified Church to be presented unto Himself, not having spot or wrinkle or any such thing Ephesians 5:26-27.