it is permissible for a person offering the obligatory Salah to be led by a person offering a supererogatory Salah, and vice versa. This is not similar to the prohibition related to making different things than that of the Imam, for the many evidences permitting that, such as the story of
Mu`adh who used to lead his people in the `Isha' (Night) Salah after having offered the same Salah with the Messenger of Allah (peace be upon him). Similarly, the Prophet led the other group of his Sahabah (Companions of the Prophet) in performing two Rak`ahs of Salat Al-Khawf (Prayer in Times of Fear) after he led the first group and pronounced Taslim (salutation of peace ending the Prayer). (Part No. 6; Page No. 307) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.