Book of Exodus is the only book in the Bible with multiple doublets for proper names. The reason for these incompleteness is because, the entire book was compiled from multiple sources. Scholars had identified at least three sources namely Elohist source, Yahwist source and Priestly source, intertwined and switched together by a later redactor (probably after exile) so that we can have it as one book and read it.

Is Moses’ father-in-law Reuel or Jethro?

Exod 2:18 When they came to Reuel their father, he said, “How is it that you have come so soon today?” 

Exod 3:1 Now Moses was keeping the flock of Jethro, his father-in-law, the priest of Midian, and he led the flock to the back of the wilderness, and came to God’s mountain, to Horeb.

What is the name of Moses’ father-in-law? Reuel or Jethro? Jethro occurs only in Elohist source and Reuel occurs only in Yahwist source.

Is God’s mountain Horeb or Sinai?

Exod 3:1,12 Now Moses was keeping the flock of Jethro, his father-in-law, the priest of Midian, and he led the flock to the back of the wilderness, and came to God’s mountain, to Horeb. … He said, “Certainly I will be with you. This will be the token to you, that I have sent you: when you have brought the people out of Egypt, you shall serve God on this mountain.”

Exod 31:18 And when He had made an end of speaking with him on Mount Sinai, He gave Moses two tablets of the Testimony, tablets of stone, written with the finger of God.

What is the name of God’s mountain? Horeb or Sinai? Are these doublets in the book of Exodus?

Conclusion

The book of Exodus is carefully stitched from several older surviving documents to use the best possible information of what happened during the first year of Exodus. Because of the dark period of Manasseh, and the exile, most of the detailed accounts from older documents might have been lost.

Deut 31:26 “Take this Book of the Law, and put it beside the ark of the covenant of the LORD your God, that it may be there as a witness against you;

2Kgs 22:8 Then Hilkiah the high priest said to Shaphan the scribe, “I have found the Book of the Law in the house of the LORD.” And Hilkiah gave the book to Shaphan, and he read it.

The book of the law must be kept beside the ark of the covenant of the LORD inside the Holy of Holies but was “lost” and found again during the days of Josiah. Hence, you must understand the state of Israel who went completely away from God and even lost their own book of the law. The above inconsistencies in the form of doublets shows us the hard work of the redactor who pieced together to recreate the events with the best of the information they have at that time so that we can read it as one book.