What feedback do you leave if you win something on eBay then seller sells it here instead? Got message earlier saying seller would be out of town so couldn't ship until Friday and now just refunded payment. Don't want to be a dick but also pretty sure seller didn't sell it until after I won it on eBay.
You can conjure bad universe karma for them, or wish a pox upon their house, which is usually more satisfying. As a seller, I don't see anything wrong with offering the same thing for sale on multiple channels - and the first to pay gets it, all others get refunded until all listings can be deleted/removed etc, so no harm no foul in the scheme of things.
By "win" do you mean you were a high bidder in an auction, or used Buy It Now? An auction item really shouldn't be listed in more than one place (my opinion), but BIN in multiple places happens all the time.