All dummy bids are illegal and attract significant penalties.

A dummy bid is either a bid: made by the vendor, in circumstances where the auction rules do not allow for such bids; and the auctioneer has not orally announced that such bids are allowed before the commencement of the auction. Or made by a person who knows that the bid is being made on behalf of the vendor.

An auctioneer must not: accept a bid at the auction if they know the bid was made by, or on behalf of the vendor, unless the bid was in accordance with the law and the auction’s rules on vendor bids falsely acknowledge a bid, where no bid was made.
Also, it is an offence for any person to procure another person to make a bid at an auction that is against the law.