@emilybee Having to redo an undergraduate thesis because someone else published on the same topic the day before is harsh. If the the two people worked independently and didn’t collaborate during the research without attribution in the paper, one could be seen as, at the minimum, confirming the other and perhaps even offering new thinking to the one question at hand. Or the advisor could have said take this new publication and incorporate it in some way.
Also, has undergraduate thesis become so difficult it is no longer sufficient to research and write a paper without it being completely original to the field? Sorry this happened to your son. That’s more PhD treatment, imho.