The previous lesson’s dual and the present sound masculine plural can both use yāʾ, but their patterns differ.
طَالِبَانِ / طَالِبَيْنِ: dual; alif nominative, yāʾ accusative/genitive; nūn has kasra.
طَالِبُونَ / طَالِبِينَ: sound masculine plural; wāw nominative, yāʾ accusative/genitive; nūn has fatḥa.
Exam point: «طَالِبَيْنِ» denotes two, whereas «طَالِبِينَ» denotes more than two male students.