It is narrated from Sayyiduna Abu Juhayfah (may Allah be pleased with him) that Sayyiduna Bilal (may Allah be pleased with him) used to say each phrase of the adhan twice for the Messenger of Allah (peace and blessings be upon him).
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18465
It is narrated from Sayyiduna Abu Juhayfah (may Allah be pleased with him) that Sayyiduna Bilal (may Allah be pleased with him) gave the adhan for the Messenger of Allah (peace and blessings be upon him) at Mina in pairs, and also said the iqamah in pairs.
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18466
Sayyiduna Abu Juhayfah (may Allah be pleased with him) said: We came to the Messenger of Allah (peace and blessings be upon him) and the time of prayer arrived, so Sayyiduna Bilal (may Allah be pleased with him) stood up and gave the adhan; he put his two fingers in his ears and began turning around. Water for ablution was brought to the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) and his (peace and blessings be upon him) Companions performed ablution. Some water was left over, and we began rushing for the leftover water of his (peace and blessings be upon him) ablution. Then he (peace and blessings be upon him) took out a spear and planted it, and the iqamah for the prayer was said, and he (peace and blessings be upon him) led the Zuhr prayer facing it as two rak'ahs and the Asr as two rak'ahs. Then he said: "When I reach Madinah, come to me." the Prophet (peace and blessings be upon him) had promised to give us some gift, and Sayyiduna Abu Bakr (may Allah be pleased with him) delivered it to us.
Hadith Referenceالمعجم الكبير للطبراني / باب الواو / 18467