Why Swarm/Lightmass "killing rogue job"?

My lightmaps works and they look great, but out of curiosity there’s still something that really confuses me.

Even on successful lightbuilds if I look through the log I see “killing rogue job”. Now perhaps this is nothing to worry about, perhaps just a few seconds wasted on this ‘rogue job’, but it might actually be a HUGE waste…

if I closely follow the swarm progress, usually what I see is this:
My computer: All 8 cores running for 40 minutes.
Network Computer: All 8 cores running for 40 minutes.

Then towards the end of the render, about 4 of the networks cores blue-line progress and 1 of my computers blue-line progress just dissapears into thin air (as if they never existed in the first place). I assume those are the rogue jobs getting killed? That perhaps the network coordinator sent some of the same jobs to both computers?

If so then those sometimes account for like 40% of my computing, which would indeed be a HUGE waste.

Any ideas?

Previously most of my swarm problems resolved around running out of ram, but now that I’ve added more ram my ram usage never goes beyond half so I know that this is not a ram related problem.