Let's look at this a different way. I have taught English to Brazilians for many years. As such, I have a pretty nice collection of Grammar books. Two of my favorites are "The Grammar Book," written by Marianne Celce-Murcia and Diane Larsen-Freeman (A very nice lady, by the way), and "English Grammar in Use" by Raymond Murphy. I see a lot of similarities between the two. They talk about the same principles, teach many of the same rules (using almost the same language) etc. So, in your opinion, who plagiarized who? Since you state that similarities are the same as plagiarism, you must believe there is plagiarism there. Of course this could be applied to many different types of text-books, such as science, math, history etc. Are they all plagiarized, then?
Despite what EP says, the language in the BoM is very different from that in the Bible, speaking in linguistic terms. The sentence structure, writing style, vocabulary etc. are all very different, except where there are quotes from the Old Testament, in which case the source cited. Can you give me a clear example of an expection? A passage in the BoM that was quoted or paraphrased without any reference to a Biblical prophet?