It sound to me like your code might be making the same API request twice.
This would result in the status getting posted and the error message you end
up with.
If you are commonly creating statuses with the same text it might just seem
like a new status is getting posted when they are not.
Abraha
I have an application that uses oAuth to post a tweet on behalf of a
user. I noticed today that when I do a status update, I'm getting a
"Status is a duplicate" error message, when in fact the status posted
correctly.
I have not changed my code, and I am using the Twitter oAuth library
(same code