Error while posting duplicate message in Twitter(MGTwitterEngine)

I am using MGTwitterEngine for iPhone to supp开发者_JS百科ort twitter, I am getting error(403) while posting a message second time how to handle this issue.

That is.. Let the message is "what are you doing" I am posting using [mTwitterEngine sendUpdate:"what are you doing"] for first time it is posted successfully, if i want to post the same message again it is throwing 403 error.

How to handle this? Can i put the alert "Duplicate message" if error no 403? Is 403 error for duplicate messages only?

Added : Is it possible to check if an message is already posted in MGTwitterEngine?

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The 403 error is not only for duplicate message so that you cannot throw the error message to user.

http://developer.twitter.com/pages/responses_errors

You have to find the duplicate message in your application code by keeping the last updated message.