For everyone who asks the High Priest to clean them, their sins will be forgiven because of the Messiah’s sacrifice at the cross. These unclean people are made clean.
After the leper was cleansed, he would “tarry abroad out of his tent seven days” This could represent the time one is in the grave awaiting for the resurrection.
The second bird was to be dipped in blood. This represents Christ coming back (Rev 19:13). The bird dipped in blood is for cleaning the house (represents the Yahweh’s temple*) and then the field (“The field is the world” – Matthew 13:38). When Christ comes back, he is going to do some major "house cleaning" to set up His Kingdom.
Revelation 19:13
And he was clothed with a vesture dipped in blood: and his name is called The Word of God.
*Note that Yahweh’s temple will be rebuilt and the abomination of desolation will be there (Dan 11:31 and Mat 24:15).
