The lamb in Revelation 5:6 is bloodied and thus appears ritually unfit for sacrifice:
And I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth.
The operative word is "appears" because appearances can be deceiving.
The rituals of the Temple foreshadow the sacrifice of the Dual Messiahs.
CLEANLINESS NEXT TO GODLINESS
Biblical religion is obsessed with cleanliness. There are two senses in which something or someone could be considered unclean: a) ceremonially; and b) morally.
A person can be morally unclean in thought and life. Some objects, such as food, things pertaining to idolatry, or even birds*, must be abstained from according to the levitical law in order that their impurity not render a person unclean.
An uncircumcised person was considered unclean by a first-century Jew. The fear of ritual impurity impeded the spread of the Gospel. Even Peter, the first pope, was slow to recognize the magnitude of shift in worldview and ritual relations wrought by Jesus Christ. In Acts 11:1ff, Peter was given a trance vision of the cleansing of the Gentiles. In verse 9, Peter was told, "What God hath cleansed, [that] call not thou common".**
In verses 16 and 17, Peter explained the meaning of the vision:
Then remembered I the word of the Lord, how that he said, John indeed baptized with water; but ye shall be baptized with the Holy Ghost. Forasmuch then as God gave them the like gift as [he did] unto us, who believed on the Lord Jesus Christ; what was I, that I could withstand God?
Like Jews before them, Gentiles are granted repentance unto life through the life-giving Spirit.
The unlikely bloodied lamb of Revelation is endowed with the same cleansing Spirit, but the depth of his gift is unique. Although Revelation 5:6 refers to the Seven Spirits residing in the lamb, the Spirit is one with seven aspects described in Isaiah 11:
 And there shall come forth a rod out of the stem of Jesse, and a Branch shall grow out of his roots:
 And the spirit of the LORD shall rest upon him, the spirit of wisdom and understanding, the spirit of counsel and might, the spirit of knowledge and of the fear of the LORD;
 And shall make him of quick understanding in the fear of the LORD: and he shall not judge after the sight of his eyes, neither reprove after the hearing of his ears:
 But with righteousness shall he judge the poor, and reprove with equity for the meek of the earth: and he shall smite the earth with the rod of his mouth, and with the breath of his lips shall he slay the wicked.
 And righteousness shall be the girdle of his loins, and faithfulness the girdle of his reins.
Thus, six of the seven aspects of the messianic Spirit are these:
fear of God.
According to Revelation 5, these gifts are unique in all the earth to only one person, who retains within himself power over destiny. This power comes to the notice of world leaders described symbolically as 4 Beast and 24 Elders.
IMPLICATION OF DUAL MESSIAHS
The perfections of Jesus Christ ritually and morally cancel the real or perceived imperfections of a successor messiah.
The indwelling of the Holy Spirit is evidence of the ritual and moral cleanliness of the believer. Because of the foundational work of the first messiah, Jesus Christ, God's choice of a second sacrificial "lamb" is open to additional considerations.
* Revelation 18:2.
** "What God has cleansed, don't you call unclean" (Hebrew Names Version).