We have proposed a technique to design spectrally encoded fiber Bragg grating (FBG) sensors allowing overlapping between two or more sensors in the same spectral region. A theoretical description of the design and the identification function for the proposed sensors has been developed. Simulation of the encoded FBG sensors was carried out to validate their overlap-proof behavior. Finally, the proposed sensors were manufactured and validated experimentally to show the compatibility between our encoding technique and traditional WDM multiplexing. Furthermore, the error of the proposed interrogation system was measured and discussed.