I was having fun in Endless mode one day, chopping endless amounts of robots to bits, when i died on level 16. It was one of those Titanium progressive 3-stage jump pad levels (the blocky one, not the building one).

Suddenly, out of nowhere, 3 of the mk 3 sword robots came up to the platform that i died in, and started swordfighting over my corpse.

I kid you not, that image is proof of them fighting each other.

This was the second platform, so it is likely they were still inactive on the third platform, and then when i died, they became active when they shouldn't have been.