The Quran that Uthman ended up producing was from the writings collected by Zaid bin Thabit who was the youngest of the collecters, rather than from some of the older collecters. The writings were not even compared, but Uthman just selected one of the collections and burned the rest.
Sahih Bukhari, 6.521: Narrated Masriq: `Abdullah bin `Amr mentioned `Abdullah bin Masud and said, "I shall ever love that man, for I heard the Prophet saying, 'Take (learn) the Qur'an from four: `Abdullah bin Masud, Salim, Mu`adh and Ubai bin Ka`b.' "
Sahih Bukhari, 6.522: Narrated Shaqiq bin...