Abstract: The present invention relates to a method of reading at least two bar codes with the aid of a reading system comprising: first and second illuminants capable of emitting respectively first and second luminous radiations having different spectral characteristics and an optical detector, the system being arranged so as to allow the reading, with the aid of the detector, of a first bar code when illuminated by the first illuminant and of a second bar code when illuminated by the second illuminant, in which method the first and second bar codes are disposed on two different substrates and in which the first bar code is read with the first illuminant and the second bar code with the second illuminant.