Every system reuses confirmations
That's why it ask for your last name at minimum
Did someone on the new one share a last name?
Read the post thoroughly, by requesting all FFC and ETC linked to your email using the tool above, I’ve received someone else’s FFC, which if you’ve ever used said tool you’d know that it includes names in the emails. The issue is that my email is (this is where the problem is) still connected to the confirmation number. Obviously, the issue isn’t recycling alone but that it isn’t washed before reuse. Hence being a United issue to my knowledge. I now have a conf number, last name, partial ffc and booked (or by now flown) itinerary.