A pure crystalline solid typically has a sharp melting point (1-3° range from when melting is first observed to when the last crystal melts). When one mixes 2 crystalline solids, the melting point is usually lower than that of either individual component and the melting point range is broadened (8-10° or more, maybe much more). However at a specific ratio of the two components, one can get a mixture that has a well-defined, sharp melting point. At that ratio, you have a eutectic mixture. In this way the homogeneous mixture exhibits the same property (sharp MP) as a pure compound.