During the time of the Messenger of Allah ﷺ, the call to prayer was made in pairs and the iqamah was made singly, except that you say, "The prayer has begun, the prayer has begun."
أخبرنا عمرو بن علي قال حدثنا يحيى قال حدثنا شعبة قال حدثني أبو جعفر عن أبي المثنى
كان الأذان على عهد رسول الله ﷺ مثنى مثنى والإقامة مرة مرة إلا أنك تقول قد قامت الصلاة قد قامت الصلاة
[Sahih] Reported by Abu Dawud, Prayer, chapter on the iqamah, no. 510, 511, from the hadith of Shuba, by this route. It is also in Kubra, no. 1593. Ibn Khuzayma graded it sahih, no. 374, as did Ibn Hibban, no. 290, 291, and Hakim, 1/197, 198, and Dhahabi. It has a corroborating witness in Abu Awana, 1/329, and Daraqutni, 1/239, and others. Its isnad is sahih.