Some targets are in separate places in the chain for the different beams, so when you have multishot on it some of them can be in 3rd and 2nd position in the different chains at times.
Plus, if you're using a primed bane mod against them, it applied twice with certain damage types that have DoT effects on a status proc. like heat for example.
The DoT effect of heat damage also functions differently from other damage types with a similar effect: slash and toxin will have a separate instance of damage for each active ticking status effect, heat combines all of the damage into one tick from