According to werner theory primary, secondary of central atom in  Pt(en)(H2O)2Cl2Cl2 Complex respectively

4Cl- satisfies primary valency, 2Cl-,en (bidentate ligand), 2 H2O satisfies secondary valency and the ligand satisfy primary and secondary valency is called duel valency, that means ligand involved in calculation of primary and secondary valency. Hence Cl- ligand act as primary and secondary valency in given complex Pt(en)2(H2O)ClCl3.