Why is Italy allowing muslims there to practive polygamy?

The second wife of a Muslim immigrant in Italy has reported her husband to police after authorities allowed his first wife  from Senegal to join the household in the northern city of Treviso. (I wonder if they all are entitled to welfare benefits from the state, too?)

AKI via TROP  The 45-year-old immigrant’s second wife, who has twin daughters of eight with him reportedly cannot countenance living with him, his first wife and their two sons of 15 and 16.

The man, who has lived in Italy for over a decade, runs little risk of prosecution for bigamy, however. Under Italian law, bigamist long-term immigrants are allowed to bring more than one wife to live with them in their adoptive country provided they are ‘integrated’.