The step sequencer has only one step level pattern it is playing at a time and L1 and L2 outputs use that same pattern.
L1 and L2 output the step value of the step sequencer, when G1 and G2 were last on respectively.
So for example when G1 is on and the step value is 0.5, this means 0.5 is output until the next time G1 is on again. This works with G2 as well.
Since G1 and G2 don’t have to be on at the same time, L1 and L2 can output a different step value.
The sampler has multiple gate inputs, so if you want to simply trigger 2 different samples then you use the G1 and G2 outputs of the step sequencer with the G1 and G2 inputs of the sampler.