That seems reasonable, whoever (I couldn't tell if it was you/a friend who one the auction) won it should e-mail the seller asking for some actual pictures of the pony that they are selling, or confirmation that the picture they used was, in fact, theirs, and that the third party was lying. If they are honest, they shouldn't become hostile/back out, and provide the pictures requested.
If the seller becomes hostile, as in, they start cussing le winner out, or tell them that they're not going to sell the pony to them, then le winner shouldn't finish the transaction, as in, not send any money, namely if they become hostile. Am I making any sense, or am I confusing you??
Thanks: VSS for Lily, and Whippet for Sig Spooky!!