What is this in the error log?

[newbieyabbie]

YaBB SE Version: 1.5.4
PHP Version: 4.3.2
MySQL Version: 4.0.x
Server Platform: Unix, Linux, or BSD
Link to Forum: www.allaboutpalestine.com/yabbse

Problem Description:
I've been seeing this error .more often lately, mostly from on IP address, byt occasionally other IP's also. Anyone knows what or why?
I should say, I haven't assigned any moderators, just two admins.

Guest : xxx.xxx.xxx: Tuesday October 07, 2003, 02:16 AM
/yabbse/index.php?board=1;action=register2
You have chosen a username of an already existing moderator. Please choose another username

[Shadow's Pawn]

You will probably want to use the Search option for this.  I've seen this before..

Try this thread too:

http://www.yabbse.org/community/index.php?thread=24298/0

Hope that helps