Potential issue with choosing the best submission of each participant

Please check these two submissions:
#15813: ranks = 6,4,4,2,4 (average=4.0)
#15919: ranks = 2,4,4,4,4 (average=3.6)
However, it seems that #15813 is chosen as my best on the public leaderboard of round 2.

Please let me know of you thoughts,
Thanks