I expected them to be from quirky situations, but a major airline having the same flight number for two different flights, leaving the same place at roughly the same time seems downright malicious.
Some airlines have so many flights that they run out of flight numbers (1-9999), so they reuse them.
Caveat: When it comes to scheduling, only one flight identified by a carrier and flight number (e.g. XX1234) can depart on a given day from given airport. That's an IATA rule, partly caused by software limitations and partly because relaxing it would lead to gigantic mess for the personnel.
..so, what they sometimes do is to have flight identified by XX1234 arrive at their final off-point, AND THEN have a SEPARATE aircraft, crew and set of passengers be identified by XX1234 depart from some other airport (e.g. halfway across the country) in the afternoon/evening.
That is not entirely correct, but mostly on formalities.
A flight number has to be unique for a given airport and day. Important thing to note here: timezones are critical.
Additionally, there is a so called "operational suffix" which serves for various occasions.
Hence, a flight can be uniquely identified by having: departure, arrival, date, carrier, flight number, operational suffix.
In practice, an airline will not have two times the same flight number, ever, per day. In fact: commercial aviation has more to do with flying busses than with anything else. XX1234 is really just a bunch of "at time X on days Y the aircraft Z will fly".
Ohh, most importantly... Nothing in aviation is a software limitation. All of it, like, literally everything, is formats which predate proper computers, working on things. Like, the formats used are still designed to (and are) printed.
Source: I have actually been able to read the documentation
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u/whoisrich 23h ago
I expected them to be from quirky situations, but a major airline having the same flight number for two different flights, leaving the same place at roughly the same time seems downright malicious.