The two spellings are Nebuchadnezzar, and Nebuchadrezzar — “n” and “r” different in each case. In Hebrew, these two letters are interchanged from time to time. Thus these two forms both refer to the same person. In the books of 1 and 2 Kings, Chronicles, Ezra, Nehemiah, Esther, and Daniel it is always with an “n.” In Ezekiel, it is always with an “r.” In Jeremiah, it is 10 times with “n” and 31 times with “r” — but always the same person intended.
Something similar happens with Achan and Achar — always “Achan” in Joshua, but “Achar” in 1 Chronicles 2:7, “Achar, the troubler of Israel.”
