I've noticed a few times that when myself and another person do something at the same time, my message will be lost on icechat (but not in logs), the line will be have part of my color and only the content from the other speaker.
I used "/me stabs TomRiddle in the diary" at the same time that Keroro said "We don't need no..."
On icechat, it appears
In the logs, it appears as
[0:09.43] <TomRiddle> like omg ded
[0:09.55] <Keroro> We dont need no bloody drums, I dont need them here.
[0:09.55] * Sems stabs TomRiddle in the diary
[0:10.16] <TomRiddle> you guys are violent
[0:10.34] * Stalin stabs TomRiddle in the harry potters forehead
[0:10.51] * Keroro stabs TomRiddle in the basilisk.
The purple at the beginning of the line on the client is the color of my action, but my action does not show. I assume it does the same if two other users speak at the same time, but obviously I can't tell unless I've looking at the log files.