A simple configuration dual-wavelength fiber laser, by combining the first-order Brillouin laser and the residual pump laser, is proposed and experimentally demonstrated. A 1 km long single-mode fiber is used as the stimulated Brillouin scattering gain medium pumped by a narrow linewidth tunable laser source (TLS). Through simply adjusting the TLS output power, power-equalized dual-wavelength lasing can be achieved with a high optical signal to noise ratio (OSNR) of $>80\mathrm{dB}$. With the good tunability of the TLS, the dual-wavelength fiber laser has a tunable range of $～130\mathrm{nm}$, and simultaneously the beat frequency of the two lasing wavelengths can be tuned from 10.1875 to 11.0815 GHz with the tunable range of 0.8940 GHz. The high stability of the dual-wavelength operation is experimentally verified by the measured beat frequency fluctuation of $\le 6\mathrm{MHz}$ in 1 h and power fluctuation of $\le 0.03\mathrm{dB}$ in 2 h. The temporal characteristics of the fiber laser are also investigated experimentally. The fiber laser will find good applications in fiber sensing and microwave photonics areas.