I don't know if I am reading this right but the way I am thinking now is are these scrapper/bots sending two out one with the username and one without?
I just got these today note both of them at the exact same time.

If I'm reading it right (this is the only one I've noticed I must add) and it starts to happen it might be better to ban bots by their IP rather than their usernames.

If I'm reading it wrong please tell me and I will remove this post.

Subject: SPIDER TRAP from xxxxx.com All headers
gotcha.php script notification
Date/Time: Sunday August 7 2005 - 6:52:51 PM
IP Address: 70.85.193.178
User agent: LWP::Simple/5.803


Subject: SPIDER TRAP from xxxxx.com All headers
gotcha.php script notification
Date/Time: Sunday August 7 2005 - 6:52:51 PM
IP Address: 70.85.193.178
User agent: Mozilla/4.76 [en] (Win98; U)