Coherent manipulation of atomic states is highly desirable in numerous applications spanning from fundamental physics to metrology. In this study, we propose and demonstrate, theoretically and experi-mentally, the simultaneous observation in a vapor cell of dark and bright resonances that provide, through a differential-detection stage, an output coherent-population-trapping atomic resonance that benefits from a doubled amplitude and high common-mode noise rejection. This advanced spectroscopic scheme might be of interest for the development of high-performance vapor-cell atomic clocks, sensors, or high-resolution spectroscopy experiments.