Need help turning off "Duplicate message in five minutes"

[stomata]

Help!!!
I am running stress testing on my site. What I am doing is having 200 users posting message however my tool can only post same message for the same user.
then I get this "This post is a duplicate of a post that you have posted in the last five minutes. You will be redirected to that thread." warning.
Is there anyone can help and tell me how I can turn it off?
, thanks!!!!!

[ssslippy]

have your script just change its msg with a one letter difference. Like go msg1 msg2 msg3