Hanafi iqamah repeats its phrases in the manner of adhan, with “qad qamat al-salah” twice.
In the Shafi‘i approach, many iqamah phrases are single, with specified repetitions for the opening takbir and “qad qamat al-salah.”
The Maliki tradition uses single repetitions for many phrases, including a narration of “qad qamat al-salah” once.
Different reports about Bilal and other companions underlie these variations.