[Butch Cassidy Slept Here]

If the trip is only one-way, involving a single, rather than connecting, flight, and is domestic, rather than international, you probably haven't got too much to worry about. Otherwise, there may, indeed, be trouble brewing. Unfortunately, if you didn't purchase a fully refundable ticket, there is little you can do, short of forfeiting the value of the ticket(s) and bookking with another airline, to stop your trip from turning to s**t. If the departure date has yet to arrive you CAN start to lay the foundation for a potential small claims action in the event things do go wrong. Send (UPS or Express Mail if necessary) copies of both confirmations to Delta Customer Service in Atlanta. If you use Express Mail send it with "Return Receipt Requested." Or, print-out a copy of the UPS delivery confirmation. As long as you can show that Delta received your correspondence prior to the departure date, and things went wrong anyway (which means they ignored your letter) you should have a solid case in Small Claims Court. Naturally, the small claims action I'm talking about would be based on a denial of boarding, or other problems, related to the matter of the duplicate confirmation number. Weather, over-bookking, delays, etc. would be entirely different matters.