Actually, I just tested the two example scripts that argv0 gave in this thread. They don't generate identical lines in the log file. The second one will get a real timestamp added in-front of the text. Interestingly, as long as timestamps are enabled for log files, there is no collision and it is always possible to determine what the original line color was (because user colors won't appear in front of the timestamp added to the log file). It is still true that there is some collision if timestamps are disabled, although again, I doubt many people turn them off (they are on by default). So again it becomes a matter of making it appear right for the majority of cases instead of being overly concerned about the possibility that collision can occur.
I also think it's important to emphasize that, with the exclusion of scripts, mIRC always uses line color to display messages. So with a default installation, there won't be any collision even if you turn logging timestamps off.
