If I put a reserve on a horse of 25,000 two things can occur. I can have a friend bid it up OR the auction house will just top each bid until it hits the reserve. Once it is past the reserve, if I have my friend continue to bid, then, if they "accidently" win the horse, I will end up getting it back plus I will have to pay the commission to the auction house on that amount. On the other hand, if the other person wants that particular horse AND THEY ARE WILLING TO PAY, what difference does it make. If it is two individuals who want the horse, or one individual and a friend of mine bidding on my horse..either way the bidding stops when one decides they will go no higher. This may be called shilling..but on the other hand..it really should not be illegal..It is up to the bidder to quit when they have reached their budget for their horse.
This occurs in art auctions, antiques, lumber, car..you name it.