Duplicate Tweet Exception for Unique Tweets


I am using a twitter4j api to reply to tweets from a java client. My replies (tweets) have a repetitive pattern but are not the same. To be more specific, they look something like
"@user <number> #a" . Only the “number” part of the tweet changes for every new tweet. Additionally, they are replies to different tweets. Although my replies (statuses) are not duplicate, I get an exception:

“403:The request is understood, but it has been refused. An accompanying error message will explain why. This code is used when requests are being denied due to update limits (https://support.twitter.com/articles/15364-about-twitter-limits-update-api-dm-and-following).
message - Status is a duplicate.
code - 187”

However, my tweets are posted successfully on twitter. Additionally, I am sure I am not hitting the update limits because I get this exception even on my first reply for the day. Could you please help me explain why I am getting this exception.



I got the same situation twice a week (in JAN 2014).
I would like to know why, too.