Originally Posted by
findark
This. Everything else is just a discussion of whether you can get away with violating the CoC. The rule is quite sensible - if everyone booked backup flights like OP wants, it would be total chaos. It only seems to be subjectively "okay" if you're the only one doing it.
Delta matches on more than just your SkyMiles number; it's not exactly hard to see two pax with identical names and dates of birth.
On top of that, too much abuse is going to drive the airlines to bring back change/cancellation fees. It’s been nice not having to deal with those and be able to flex tickets without penalty but this sort of practice is how we see the no change/cancellation penalties reversed.