Why are there two calls to prayer (adhan) for Jumu'ah (Friday prayer), even though the Prophet, peace and blessings be upon him, had only one call to prayer made in front of him when he ascended the minbar?

In the era of the Prophet, peace and blessings be upon him, the Adhan (call to prayer) was a single call followed by the Iqama (second call to prayer). However, during the reign of Uthman ibn Affan, may Allah be pleased with him, the population of Medina increased. Therefore, he added a third Adhan (the first Adhan) to alert people about Friday. This was an ijtihad (independent reasoning) by Uthman, may Allah be pleased with him, and the Companions followed him in it. This is part of the Sunnah of the Rightly Guided Caliphs, based on the Prophet's saying, peace and blessings be upon him: "Hold firmly to my Sunnah and the Sunnah of the Rightly Guided Caliphs after me. Cling to it and bite onto it with your molars."