When the sun was eclipsed during the time of the Messenger of Allah ﷺ, a call was made, "The prayer is being gathered." The Prophet ﷺ performed two bowings within a single unit followed by prostration, then he stood and performed two more bowings within a single unit followed by prostration, then he sat until the sun was cleared.
لما كسفت الشمس على عهد رسول الله ﷺ نودى: إن الصلاة جامعة فركع النبي ﷺ ركعتين في سجدة، ثم قام، فركع ركعتين في سجدة، ثم جلس حتى جلي عن الشمس.
Bukhari narrated it in the Chapter on the Eclipse (1051), and Muslim in the Chapter on the Eclipse (910), both through Abu Muawiya, from Yahya bin Abu Kathir, from Abu Salama, from Abdullah bin Amr bin As, and he related it as mentioned. It has already been cited.His saying, "two rakats in one sajdah," means two rukus in each rakat, and this is what is meant by "four rakats in two rakats." His saying "in a sajdah" means "in a rakat."As for what the compilers of the Sunan narrated, limiting each rakat to a single ruku, that is anomalous. Abu Salama preserved from Abdullah bin Amr the report of two rukus in one rakat, and this stands as proof against whoever did not preserve it correctly.Likewise, what Nasai narrated (1482) through Ata bin Saaib is not sahih. He said, Abu Saaib narrated to me that Abdullah bin Amr told him, and in it he said, "He prolonged the sitting," meaning between the two sajdahs. But Ata bin Saaib was known to have become confused in his narrations later in life, and he was not corroborated in this report, and none of the people of knowledge have spoken of prolonging the sitting between the two sajdahs.