It seems that the team won the first and second places may have multiple accounts. They summited the semi-results through these accounts (register with different names) and prepared for there final submissions.
It does broke the rule and fair of this competition. it is better to check through all the submission's attribute to see if the creators or owners of these files are come from the same serves or PCs.
As far as I observed, many teams have two or more accounts in the second phase. I strongly against this kind of behavior.