محمد بن يحيى ، عن محمد بن الحسين، عن عبد الرحمن بن أبي هاشم ، عن سالم بن سلمة قال : قرأ رجل على أبي عبد الله ( عليه السلام ) وأنا أستمع حروفا من القرآن ليس على ما يقرؤها الناس ، فقال أبو عبد الله ( عليه السلام ) : كف عن هذه القراءة اقرأ كما يقرأ الناس حتى يقوم القائم فإذا قام القائم ( عليه السلام ) قرأ كتاب الله عز وجل على حده وأخرج المصحف الذي كتبه علي ( عليه السلام )A man read several verses of Quran for imam “Sadiq” [AS], I listened to it, he wouldn’t read based on the method that people would read. Imam “Sadiq” [AS] told him: avoid this reading and read like other people until hadrat “Mahdi” [AS] appears and when he appears, he’ll come with the Quran that “Ali” [AS] had written.

Quran is guarded by Allah as it came in Quran
Holy Quran 15:9
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إِنَّا نَحْنُ نَزَّلْنَا الذِّكْرَ وَإِنَّا لَهُ لَحَافِظُونَ

Indeed, it is We who sent down the Qur’an and indeed, We will be its guardian.
Quran is complete nothing added to quran or deducted from Quran.
Only the difference is order of the revelation.Imam Ali as has complied according to the actual revelation order and the other one it was compiled by Ashab in the time of uthman which is complete but not according to correct order of the revelation.