FAKE PROFILES IN CONTESTS AND HARASSMENT

I judge my contests blind.  In other words, I don't know who the poets are until I've finalized the contest and look at the winner's page. 

However, I have been recently apprised that the second place winner in my Midnight Romance contest,  is very likely a fake profile created by one of our member poets(it's the only poem on her profile). 

I want to continue to judge blindly.  Perhaps the only remedy is to require a certain form, then look at who has posted under that form and compare to my contest entries.  I can then make sure that poets in question don't advance past the first round and expand the number of entries for each one I find. 

The problem that creates is for new poets entering contests for the first time.  What else can I do?  Does anyone else have better remedies? 

I have been warned that three poets(whom I will not name) not only have fake profiles to the extent they enter their own contests and come in the top ten, but they use these fake profiles to harass other poets with negative comments and enter contests under multiple names.  This isn't fair to other poets as it takes away their chances to enter contests and even place in them!

I honestly do not know what the answer is, but before I host another contest I hope I will have figured something out.

Sincerely