Version:           revision 570312 (using KDE KDE 3.5.4)
Compiler:          gcc (GCC) 4.1.2 20060715 (prerelease) (Ubuntu 4.1.1-9ubuntu1)  
OS:                Linux

If you're talking to a person in a /query window, and then type /dcc chat nick, konversation creates an additional logfile with the person's name between dashes, so $server_-$nick-.log if you then look in the logs directory, you've got two log files for the same person. $server_$nick.log and $server_-$nick-.log

If the person you're chatting with changes his nickname while you're having a DCC chat conversation, the nick in the channel updates, but the one in the DCC chat tab does not. And when you then close and reopen the /query window, another log file is added for the changed nickname. 

I also noticed that /query conversation log files are being lower-cased, whereas DCC chat conversations are not.
I suggest picking one style and sticking with it.

So... to reproduce;

1. Enable "Follow nick changes".
2. Open query with someone. (by typing /query $nickname)
3. Exchange some messages. 
4. Notice the log file being created. ($server_$nickname.log)
5. Open a DCC chat window with that person. (by typing /dcc chat $nickname)
6. Exchange some messages.
7. Notice a second log file being created. ($server_-$nickname-.log)
8. Close the query window.
9. Have the other user change his nickname.
10. Notice the nickname changing in the channel and the one on the DCC chat tab staying the same.
11. Open a /query with the person again.
12. Exchange some messages.
13. Notice how a third log file is created. ($server_$changednickname.log)

Expected behavior;

I expect konversation to disregard the fact that I'm having a DCC chat konversation with the user. It should create 1 log file and use that for both types of conversation methods.