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From memory 'ALL' Sedo users who wish to place bids over $10,000 need to have gone through the Premium Certification process e.g. Submission of a certification application, a bank statement or utility bill, and a photo ID.
So if such a bid was placed and not fulfilled, you would 'hope' Sedo would ban the user from participating in any further auctions further down the line.
In some cases I've know high opening bids to take place due to previous pre-sale discussions with the sellers prior to sending the name to auction.. Fingers crossed it's all genuine for those involved.