there is only one unique YHWH.
There is only one unique YHWH = “belief in the one, only and unique God”.
”1. The one God. (a) theos is the most frequent designation of God in the NT. Belief in the one, only and unique God (Matt. 23:9; Rom. 3:30; 1 Cor. 8:4,6; Gal. 3:20; 1 Tim. 2:5; Jas. 2:19) is an established part of Christian tradition. Jesus himself made the fundamental confession of Jud. his own and expressly quoted the Shema (Deut. 6:4-5; see Mk. 12:29-30; cf. Matt. 22:37; Lk. 10:27). This guaranteed continuity between the old and the new covenants. The God whom Christians worship is the God of the fathers (Acts 3:13; 5:30; 22:14), the God of Abraham, Isaac and Jacob (Acts 3:13; 7:32; cf. Matt. 22:32; Mk. 12:26; Lk. 20:37), the God of Israel (Matt. 15:31; Lk. 1:68; Acts 13:17), and the God of Jesus Christ (2 Cor. 1:3; Eph. 1:3; 1Pet. 1:3).”
(New International Dictionary of New Testament Theology, Abridged Edition, p. 244)
The one unique YHWH is a plurality, which is why two in the verse are both called YHWH.
The one unique YHWH / the one, only and unique God is the God whom Christians worship, the God of the fathers, the God of Abraham, the God of Isaac, the God of Jacob, the God of Israel, and the God of Jesus. That fact is emphasized in the verse.
Who is the God of Jesus? YHWH.
Who is the God of Jesus? The Father.
There is no plurality in the God of Jesus.
There is no God besides the God of Jesus.
Who is the God Christians worship? The God of Jesus.
Who is the God of the fathers? The God of Jesus.
Who is the God of Abraham? The God of Jesus.
Who is the God of Isaac? The God of Jesus.
Who is the God of Jacob? The God of Jesus.
Who is the God of Israel? The God of Jesus.
Who is my God? The God of Jesus.
Who is your God?
”… as for me and my house, we will serve YHWH.” - Joshua, whose God is the God of Jesus.