There was no pre-Christian, official and authoritative so called Greek Septuagint. What passes for the LXX today is nothing more than the Vaticanus, Sinaiticus and Alexandrinus manuscripts, all of which were written some 250 to 300 years AFTER the New Testament was already complete.
If there had been an authoritative pre-Christian LXX in wide use and circulation, there would not have been any need for people like Jerome, Aquila, Symmachus, Theodotian, Lucian and Hesychius to make their own translations years later. There are several so called Septuagints out there and none of them agree with the others.
There are only a few remaining scraps that could possibly be dated as B.C. writings, and even those sites that mention them tell us that they do not agree with other Septuagint copies. In all likelihood they are nothing more than the confused remnants of an independent individual's own attempt at a translation, just as several others did at a later date.
Textual criticism is for me a tangential interest. I do not profess to anything more than a basic understanding and grasp of this scholarly venue......nothing more. But even I am sufficiently informed to know that there is MASSIVE influence in our present day NT by the Greek LXX.
Quotations from the Lxx. In the New Testament. (biblehub.com)
(e) More than half of the direct quotations from the O.T. in the Epistles of St Paul are taken from the LXX. without material change (Rom. i.17, ii.24, iii.4, iv.7 f., 18, vii.7, viii.36, ix.7, 12, 13, 15, 26, x.6 ff., 16, 18, 19, 20 f., xi.26 f., 34f., xii.20 f., xiii.9, xv.3, 9, 10, 11, 12, 21; 1 Cor. iii.20, vi.16, x.7, 26, xv.32; 2 Cor. iv.13, vi.2, viii.15, ix.9; Gal. iii.6, 10, 11, 12, iv.27, v.14; Eph. iv.16; 2 Tim. ii.19). A smaller proportion skew important variants (Rom. iii.20 = Gal. ii.16 pasa sarx for pas zon LXX.; ix.9 kata ton kairon touton eleusomai, kai estai te Sarra huios for hexo . . . kata ton kairon touton . . . kai hexei huion Sarra LXX.; ix.17 eis auto touto exegeira se for heneken toutou dieterethes, and dunamin for ischun LXX.
[834] ; ix.27 ho arithmos ton huion I., epi tes ges; xiv.11 zo ego for kat' emautou omnuo, exomologesetai to theo for omeitai ton theon LXX.; 1 Cor. i.19 atheteso for krupso LXX.; Gal. iii.8 panta ta ethne for pasai hai phulai tes ges LXX.; iii.13 epikataratos (cf. v.20) for kekataramenos LXX.; Eph. iv.8 edoken domata tois anthropois for elabes d. en anthropo
[835] LXX.; iv.25 meta tou plesion for pros ton pl. LXX.; v.31 anti toutou for heneken t., om. autou 1º, 2º; cf. Mt. xix.5 f., Mc. x.7 f.; vi.3 kai ese makrochronios for k. ina makrochr. gene).
