It is narrated from Zuhrī, that Sayyidunā Abu Bakr rađiyAllāhu ánhu name is Abdullah bin Uthmân bin Aamir bin Amr bin Ka’ab bin Sa’ad bin Taeem bin Marah bin Ka’ab bin Laueey bin Galib bin Fahr.[1]
Ummul Mu’minīn Sayyidāh Ayesha rađiyAllāhu ánha has narrated that Sayyidunā Abu Bakr rađiyAllāhu ánhu was given the name Abdullah bin Aamir bin Amr by family members, but was known as Attīq.[2]

Sayyidunā Layth bin Sa’ad narrated that Sayyidunā Abu Bakr rađiyAllāhu ánhu was given the name Attīq, by the kindness [and mercy] of the Beloved Prophet śallAllāhu álayhi wa sallam. Your real name was Abdullah bin Uthmân.[3]

Abu Hafs Amr bin Ali rađiyAllāhu ánhu narrates that Sayyidunā Abu Bakr rađiyAllāhu ánhu blessed face was [of a] light [complexion] and your blessed name was Abdullah bin Uthmân.[4]

Amir narrates from his father Sayyidunā Abdullah bin Zubayr rađiyAllāhu ánhu that Sayyidunā Abu Bakr rađiyAllāhu ánhu’s name was Abdullah bin Uthmân.[5]
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[1] Hâkim, al-Mustadrak, vol. 3, pp. 64, Hadīth 4403
Imâm Bayhaqī, Sunan al-Kubra, vol. 6, pp. 369, Hadīth 12870
[2] Shaybāni, Al-Âhād wa al-Mathānī, vol. 1, pp. 70
[3] At-Tabarânī, Mu’jam al-Kabīr, vol. 1, pp. 52, Hadīth 4
Haytamī has stated in Majma’ al-Zawâ’id [vol. 9, pp. 41] that this has been narrated to us by at-Tabarânī and all the narrators are trustworthy [thiqqa].
Shaybāni, Al-Âhād wa al-Mathānī, vol. 1, pp. 69
Ibn Hajar Asqalânī, al-Isaba, vol. 4, pp. 170
[4] Haytamī, Majma’ al-Zawâ’id, vol. 9, pp. 41
[5] Ibn Hibbān, Sahīh, vol. 15, pp. 279, Hadīth 6864