Exploiting a specially designed Fabry-Perot filter as output coupler, a continuous 1 052 nm and 1 061 nm dual-wavelength laser is realized. The threshold, slope efficiency and maximum power of the 1 052 nm and 1 061 nm dual-wavelength laser are 2.55 W, 17.5% and 571 mW, respectively. The competition and coexistent relationships between 1 052 nm, 1 061 nm and 1 064 nm are analyzed. Involved non-degenerate Stark energy level structures are used to classify dual-wavelength lasers. According to this method, dual-wavelength lasers can be classified as different upper and lower non-degenerate Stark energy levels, the same upper but different lower Stark energy levels, different upper but the same lower Stark energy levels. Representative Nd:YAG dual-wavelength lasers are classified according to this criterion. It is found that the realization of front two type lasers is easy and that of third type lasers is challenging. This method can be used as a level of difficulty reference for the realization of dual-wavelength lasers.