This work reports for the first time the study of an artificial saturable absorber based on a non-linear amplifying loop mirror (NALM2) with two independently pumped active media instead of one (NALM). It is demonstrated that an adjustment of the ratio of the pump source power levels leads to a variation of the saturable power of an NALM2-based artificial saturable absorber within relatively broad limits. The transmission dependence of NALM2 upon peak power and variation of its shape as a function of the ratio of pump source power levels are established. The dynamics of the duration and shape of picosecond pulses at radiation peak powers close to the saturation power of NALM2 is also studied. It is shown that proper adjustment of the ratio of pump source power levels allows the maximal NALM2 saturation power to be shifted into a higher peak power of radiation pulses. The identified properties of NALM2 make it a universal saturable absorber for mode locking in fibre lasers with a variable peak pulse of ultra-short output pulses.