I got lost on the Muhammad part (Muhammad, Mahmoud, Ahmad and Hamid are four different names and not 'variant spellings'), but apparently it does show something about the popularity of Arab names in the city.
Variants of Islamic prophet's name discovered to be most popular among baby names in Milan
What is the most popular name for children born in the Italian city of Milan? The city's municipality reported what some may find a strange turn of events on the subject: The names Mahmoud, Ahmad, and Hamid are currently the most popular names given to infants born in the economic capital of Italy.
The Saudi newspaper al-Watan reported that the reason for the names' newfound Italian popularity is due to the rising birthrate among the city's Muslim community.
According to al-Watan, the Milan Municipality did not overlook the figures, and directed the local media to report their concern for the issue, which is "worrying to Milan's society," in order to warn against the "growth of the religion of Islam and the Muslim community, which may change the cultural characteristics of the city."
Immediately following the name of the Islamic prophet in order of popularity is the name Omar, and next in line are some Italian names – Andrea, Alessandro, Davida, Marco, Alicia, and Sophia.
Source: Ynet (English), h/t Dhimmi Watch
See also: Malmö: 2007 Baby names, Oslo: Muhammad most popular boy's name, UK: Muhammad second most popular name