A novel scheme to generate tunable dual-wavelength optical pulses with low timing jitter at arbitrary repetition rates is proposed and demonstrated experimentally. The pulses are generated from a gain-switched Fabry-Perot laser diode with two exteal cw beams for injection seeding simultaneously. The cw light is generated by two independent distributed feedback laser diodes, and their wavelengths can be tuned independently by two temperature controllers. The dual-wavelength pulses with the pulse width of 57 ps, the timing jitter of 340 fs, are obtained. The sidemode-suppression ratio of the output pulses is better than 23 dB over a 10-nm wavelength tuning range.