According to werner theory primary, secondary of central atom in  Pt(en)H2OCl3Cl Complex respectively

4Cl- satisfies primary valency, 3Cl-,en (bidentate ligand),  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.