This seems decidedly like something AA's flight database should catch and prevent. Has AA been vibe coding or is this just an edge case that had never been tested before?
A flight number, I believe, is assigned to a regular round trip in general. So this is no more unusual than, say, the 42 bus arriving at the stop as the 42 bus is departing across the street.
Sure the same flight number can sometimes be used on distinct flights (especially when one plane completes multiple segments successively), but the flights should generally not be operating simultaneously, and definitely not in the same local airspace. Some nice comments here: https://www.reddit.com/r/aviation/comments/1voj922/2_planes_...
Buses each have individual identifiers, even if they are tied to the same route.