A chipless radio frequency identification (RFID) system based on multi-resonant-based chipless RFID tags and fractional Fourier transform (FrFT) was simulated. Each tag codes a 3-bit unique identification (ID) in the form of a spectral signature in the interrogation signal. The signal is then backscattered to the processing unit (PU) for ID decoding. The simulated system accounts for two tags, 1 m apart and with a line-of-sight between them and the PU. At the PU, the received signals from the tags at 4 and 5 m present a signal-to-noise ratio of 7.9 and 4.0 dB, respectively. The signals from both tags collide in the time and frequency domain. FrFT is used at the PU to retrieve the ID of each tag by transforming the combined received signal from the time-frequency domain to a fractional domain where each backscattered signal takes its most compact form. Using Hamming windowing in the fractional domain, each ID was successfully recovered. This work puts chipless RFID one step closer to become a reality and replacing the barcode in the labelling market.