Unmotivated practice melee fighters in arenas

[tos1]

Some guys don't fight till receive an attack from others.

- How to reproduce it/when/why it happens:
This seems to be easily recreated. Whenever and wherever I fought a melee in an arena to the end, I see at least 4 or 5 "standing" men. (I'm testing as a non-lord character now)

- Computer specs:
Laptop, Win8.1 64bit, Core i7-4600M 2.9 GHz, 8 GB memory, GeForce GT 730M

- Game version (and steam or downloaded):
AWoIaF v8.1, Downloaded (I have not seen this with v7.11.)

- Additional information (Screenshots etc):
In the first example, only the guy "A" is challenging me. The "B" is only standing and facing to "A". The "C" came later but the same, he does only stand and facing to "B". The "B" (or "C") starts his fights after I knocked down "A" or he received any attack from some other guys. (In many cases, "C" challenges to one of "A", "B", or me. )

In the second example, the "D" and "E" face each other without doing their fight till someone attacks one of them.