Shia Hadith: Mahdi is the Messiah and his name is 'Al-Ghulam'

The eminent Shi’i scholar Mirza Hussain Nuri Tabarsi (1838-1902)  has compiled ahadith of the Hol Prophet Muhammad(saw) in Al-Najm al-thāqib fī aḥwāl al-imām al-ghāʾib. Interestingly these ahadith support the Ahmadi view of the Mahdi.

The ahadith in the book mentions the title Masih al-Zaman (“Messiah of the Time”) and al-Ghulaam (“Servant”) as names of the promised Mahdi, and that from among the people he shall most resemble Jesus son of Mary in both appearance and behavior:

Reference: Al-Najm-ul-Thaqib  v. 1, pp. 202, 218, 272

If the Mahdi is resembling Jesus, son of Mary and is called the Masih of his time then the question is why is Jesus(pbuh) needed?

Mirza Hussain Nuri Tabarsi  mentioned that the Mahdi is also named as Baqiyat-ul-Ambiyaa (lit. “Remainder of the Prophets”):

Reference: Al-Najm-ul-Thaqib; v. 1, pp. 177-178