Given the re-submission penalty, in Codeforces Round #198 (Div. 2), I faced the loss of 50 points, thanks to a double request sent to the server in my only submission to problem A, which ultimately led to a difference of 281 places in terms of rank.
I'm not sure, whether if there's a solution to this problem or not. That's why I posted in here.
But I believe that there should be more precautions to avoid such a problem, as usually this is out of one's will to do that. Something like a confirm message such as that done at TopCoder, or comparing it with a previous submitted codes, such that one can't submit the same code more than once in the same Contest, or something like that.