Double salts are addition compounds that lose their identity in an aqueous solution and completely dissociate into simple constituent ions. For example, Potash alum, $KAl(SO_4)_2 \cdot 12H_2O$, is a classic double salt that dissociates into $K^+$, $Al^{3+}$, and $SO_4^{2-}$ ions in water. On the other hand, coordination complexes retain their identity in the solid state as well as in an aqueous solution and do not dissociate into all of their constituent simple ions. The compound $K_2PtCl_2 \cdot 2NH_3$ represents a coordination complex. Therefore, the set containing a complex and a double salt respectively is $K_2PtCl_2 \cdot 2NH_3$ and $KAl(SO_4)_2 \cdot 12H_2O$.