The A-story of the bounce house starts with the fact that Rudy's bounce house was cancelled due to thinking it was a duplicate order to the one for Dahlia's birthday party. However, the orders would have had different names, addresses, and payment information on them. The difference would have been clear enough to recognize that they were indeed different orders, or at least enough that they would follow up, call and confirm whether they were separate orders. The cancellation was early enough that they're fully booked now, there was time to call.