Br Mehdi Ali Khan, please don't be offended by words of Shangrila Suhag. Though Mahdi is a known pronounciation in Arabic language. There are more Mehdis in India, Pakistan, Bengladesh and Iran then anyone can imagine. Your parents spelled it correctly according to the culture and place they were. Had they named you Mahdi, your schools friends would have bullied you calling maadi (ie a female bird etc) or in Punjab they will call you ( maan di.., a real bed word). Please note when Salman Farsi RTA came to Arab from Iran, Muhammad SWS did not change his name to Quranic Suleman PBUH.