Are those who lead the congregation in prayer permitted to repeat God’s Name in blessings or in prayers?
The reason for the prohibition of repeating words in the Amidah found in Mishnah Berakhot 5:3 (and Megillah 4:9) was the fear of giving the impression of praying to two divinities. This fear probably stemmed from the historical context in which Judaism was defending itself against the ideas of the Gnostics who believed in dualism. This fear had already disappeared in the Middle Ages, and, as a result, the editors of various prayer books included repetitions such as Hashem Hashem, Hashem Hu Ha’elohim, Kol Haneshama Tehallel Yah, and Hashem Yimlokh L’olam Va’ed. Furthermore, it was also the custom of cantors to repeat words and sentences in the prayers.
One should avoid repeating words or sentences in the prayers if it brings inconvenience to the public, or if it diminishes the sacredness of the prayers. On the other hand, it is permissible to repeat words, including God’s name, or sentences in the prayers, when it is done in order to increase kavanah and the involvement of the congregation in prayer.
Rabbi Gilah Dror