The Shudra should take only one wife from his own caste. He can, under no circumstances, take any other wife. Even if he happens to have a hundred sons by this wife, all of them share equally the property that he may leave behind.
शूद्रस्य स्यात् सवर्णैव भार्या नान्या कथंचन। समभागाश्च पुत्राः स्युर्यदि पुत्रशतं भवेत्॥