"At the time of the Messenger of Allah ﷺ the phrases of the Adhan were said twice and the phrases of the Iqamah were said once, except that you should say: 'Qad Qamatis-Salah, Qad Qamatis-Salah (prayer is about to begin, prayer is about to begin).'" (Using translation from Nasāʾī 628)
كَانَ الْأَذَانُ عَلَى عَهْدِ رَسُولِ اللهِ ﷺ مَثْنَى مَثْنَى وَالْإِقَامَةُ وَاحِدَةً غَيْرَ أَنَّ الْمُؤَذِّنَ كَانَ إِذَا قَالَ قَدْ قَامَتِ الصَّلَاةُ قَالَ قَدْ قَامَتِ الصَّلَاةُ مَرَّتَيْنِ