The Imam should be followed by the Ma'mums (people being led by an Imam in Prayer). The Prophet (peace be upon him) asked us to follow him when he said,
Imam is meant to be followed, so when he pronounces Takbir (saying: "Allahu Akbar [Allah is the Greatest]"), do like what he does. When he performs Ruku` (bowing), do like what he does.
It is impermissible not to follow the Imam in Sujud-ul-Sahw intentionally. You have to repeat the mentioned Salah.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.