I believe that there are at least ten known persons called the "Mahdi". The most notable was Mohammed Ahmed al Mahdi (1844-1885). He swept the Sudan clear of Egyptian rule. His fanatics killed General Gordon, who was an adviser to the defenders of Khartoum.
After his triumph, he died of typhus. A magnificent tomb was built for his remains. Herbert, Lord Kitchener, with the British army and Egyptian allies, defeated the Mahdi's successor. Kitchener's men destroyed the tomb. They desecrated the remains of the Mahdi. They threw the remains in the River Nile. His scull was sent to Cairo.
A successor was quickly chosen. He was the "Khalifa". Abullah Ibn Mohammed. Born 1846 and died fighting the British 1899. The slaughter by American made machine guns of the fanatical dervish at Omdurman 1898, is legendary stuff.
The tomb has been rebuilt and is a tourist attraction.
This illustrates why I don’t believe that the Anti-Christ will be the Mahdi.
The different sects of Islam will never accept the same man as the Mahdi.
They didn’t in these instances and they won’t accept any future man as the Mahdi.
The power structures of the various sects will never agree to consolidation of power in the same man.