Is it incumbent upon the latecomer (masbuq) to perform the prostration of forgetfulness (sujud al-sahw) after completing his prayer if his imam performed it after the taslim or before it, and is it possible to perform the prostration of forgetfulness twice?

If the Imam prostrates for forgetfulness (Sajdah al-Sahw) before the salutation (taslim), the latecomer (masbuq) must follow him and prostrate again after completing what he missed, unless the Imam's forgetfulness occurred before the latecomer joined him, in which case he does not repeat the prostration. However, if the Imam's prostration is after the salutation, the latecomer does not prostrate with him. But if the Imam's forgetfulness occurred before the latecomer joined, there is no prostration due upon him. If it occurred after he joined, the latecomer prostrates when he gives the salutation, because the Prophet, peace and blessings be upon him, said: "Indeed, the Imam is appointed to be followed."