Simultaneous Reservations
 

I'm not even sure the correct words to describe this, much less to search for it successfully. We have airline tickets ATL-YVR for a certain date. Due to concern about a personal matter, we might find ourselves in NYC instead of ATL. Putting aside travel insurance and other measures to mitigate the cost, what I would like to avoid is there not being any seats to accommodate us NYC-YVR.

It just so happens that Delta is the airline for both flights.

Will they notice that we have two reservations for which we cannot possible use both? Will they care? Clearly, I would book the second reservation fully refundable and cancel it the day before if I know we'll be in ATL as originally planned. Will there be other problems with this approach of which I'm not aware?

If you don't put your FF # in, and use a different cc, I doubt DL can spot this.

You should be ok. The safer thing would be to book a ticket NYC-ATL

Theoretically yes. They can see the second reservation and cancel one or both since it's impossible to be on both. Realistically the chance is low. I've never experienced, nor heard of anyone experiencing it.

Leave your SM# off the ticket, and only add it the day before once you know which you'll be taking.

The ATL-YVR flight leaves ATL earlier than we'd be able to leave NYC, so we would have no option other than to go straight from NYC to YVR.

Not part of Skyteam, but there is the nightly CX flight non-stop from JFK to YVR .

DL's upgraded anti-fraud software is much more sophisticated. Leaving your SM # off the ticket won't do a thing. You may or may not get caught and, if you do, DL may cancel one or both tickets and it may or may not contact you before doing so.

If you want to do this, book your NYC-YVR on AC, WS, CS, or PR, all of which have nonstop service on that route as well as DL.

Everything you wrote is entirely true. In theory. I don't think I've ever read a post about it actually happening. The only time I've heard of a ticket being cancelled is someone booking 2 separate reservations for the same person on the same flight.

Every airline deletes duplicate reservations, even Southwest with their behind-the-times IT system.

Change your ticket when you need to change your plans instead of being greedy and hogging seat inventory. :td:

I've had multiple reservations and it's not been a problem, even with my FF# in both. Once my issues settle, I do cancel so that it's back in the pool.

That's probably a better idea.

There's theory, and then there's practice.

Delta could - and I emphasize could - scan reservation records for duplicate names and birth dates. Those are statistically very improbable. They don't need SkyMiles numbers or credit card numbers. I don't believe they scan improbable duplicate names/birth dates for impossible flight combinations.

As for duplicate reservations, with two bookings on the same flight - oh, yes, they do look for that. Been there. Been caught - pretty quickly, I will add.

If the OP thinks Delta's duplicate detection is very advanced he might wait. What's the real benefit of duplicates here, anyway?

Ensuring that if the worst happens, and we find ourselves in NYC instead of ATL, that there are still seats available on flights from there to YVR so that we don't arrive in YVR too late.

I have been involved with a similar situation at least three times where they did catch the duplicates on different routes flying
at the same time. Even not entering the SM number didn't help. They caught it anyone (one was a SM ticket). I wouldn't risk it, but
you never know.

I think it's urban legend that Delta will cancel a ticket in the situation OP describes. It's entirely different than duplicate reservations (I.e. 2 seats on the same flight for the same passenger).

In fact, I have been specifically told to book tickets like OP wants to when my plans changed. I was flying YYZ-ATL and plans changed about 2 weeks out and I needed to get to Vegas. It was cheaper to book a new YYZ-LAS than to add ATL-LAS to the end of my trip, so the agent said to book the conflicting YYZ-LAS and just leave the YYZ-ATL because the value of the ticket was less than the change fee, and there would have been $0 residual value if I cancelled the YYZ-ATL. In another situation, I needed to get to LGA instead of ORD, and was advised to book both and take the one I needed.

This happens to me about once a year, I have been explicitly told to book the conflicting segments, and have never had a problem.