Optical signals of two different wavelengths in the IR regime were generated in atomic Rb vapor using broad bandwidth laser pulses. Competition between the two signals was observed. The effects of pump laser intensity, chirp of laser pulses and Rb number density on the characteristics of the two signals were investigated. The results show that the two signals were generated from two coupled parametric six-wave mixings processes and the competition between the two signals was dominantly governed by phase matching conditions related to Rb number density.