A multiple conversion superheterodyne receiver is more susceptible to spurious responses than a single-conversion receiver because of the:

Multiple-conversion superheterodyne receivers use two or more local oscillators and mixers to step the incoming RF signal down to the final intermediate frequency (IF). Each time an oscillator mixes with a signal, it creates sum and difference frequencies, as well as various harmonic combinations. Because of the larger number of oscillators and mixing stages, the receiver generates many more internal mixing products. If any of these internal mathematical combinations happen to land within the receiver's tuned passband, they are heard as unwanted spurious responses or "birdies." Distractors involving AGC overload or poorer selectivity are incorrect because spurious responses are fundamentally a frequency-mixing mathematical issue, not a gain or sensitivity problem.