There are two versions of the old testament, a Greek version, and a Hebrew version. The Masoretic Text is written in Hebrew and is dated to around 900-1100 AD. On the other side, there is the Septuagint (aka the LXX) which is a Greek translation of the Old Testament that goes back before the time of Jesus to around 300 BC. The Masoretic Text preserved the Hebrew since, for the layman Jews, spoken Hebrew had faded out of use by then and had been replaced by the Aramaic spoken by the empires that ruled Israel since Babylonian Exile. Some suspect that Jews tampered with the Masoretic Text to cover up messianic prophecies (like Psalms 22:16). While others suspect that this Septuagint was corrupted by Jews that adopted Greek philosophy and altered the meanings of certain scriptures. Then are those that see value in both and recognize that when one has errors the other offers a solution.