That article is disingenuous in taking the 1961 survey - the Hindu Marriage Act was just enacted 5 years in 1955 and made polygamy illegal for Hindus. Figures taken today would be vastly different.
There is no State Legislation in India governing Muslim Marriage. According to Muslim Personal Law (Shariat) Application Act 1937, the subject of Marriage is included in the List of subjects (Section 2 of the Act) on which Courts will apply only Muslim Personal Law, as a rule for decision where both the parties are Muslim. Muslim Personal Law permits multiple marriages for the Male and it is not illegal for a Muslim Male to marry a second time during the subsistence of his first marriage.
