Verse in Question:
Genesis 19:24 New International Version
Then the LORD rained down burning sulfur on Sodom and Gomorrah–from the LORD out of the heavens.
Does this verse actually mean there are two Yahwehs? No, this is an example of Biblical Duplication that we can find in the Bible. Below are a list of such ‘duplicates’:
1 Kings 8
8 Then Solomon assembled the elders of Israel, and all the heads of the tribes, the chief of the fathers of the children of Israel, unto king Solomon in Jerusalem, that they might bring up the ark of the covenant of the Lord out of the city of David, which is Zion.
Exodus 34:29-35King James Version (KJV)
29 And it came to pass, when Moses came down from mount Sinai with the two tables of testimony in Moses’ hand, when he came down from the mount, that Moses wist not that the skin of his face shone while he talked with him.
Young’s Literal Translation
and the priest doth pour of the oil on the left palm of the priest;
Similar repetition is seen in Ezekiel 11:24 (“Spirit” x2), Zechariah 10:12 (“Yahweh” x2), Genesis 17:23 (“Abraham” x2), and 1 Kings 8:1 (“Solomon” x2), Exodus 34:29 (“Moses” x2), Leviticus 14:15 (“priest” x2), Leviticus 14:26 (“priest” x2), Genesis 37:28 (“Joseph” x3), 1 Kings 12:21 (“Rehoboam” x2)