How many tashahhuds must one who caught the second rak'ah of the Maghrib prayer perform until the end of the prayer?

Scholars differed concerning the ruling on the tashahhud. Some, like Malik and Abu Hanifa, held that it is a Sunnah and not obligatory. Others, like Ahmad and Al-Shafi'i, considered it obligatory, citing the hadith of Ibn Abbas that the Messenger of Allah, peace and blessings be upon him, used to teach them the tashahhud just as he would teach them a chapter from the Qur'an. The questioner should perform the tashahhud in both sittings with the Imam, and then perform the tashahhud again after completing the missed rak'ah and before the salutation.