Ok... I think I may know why it's happening:
One report is from the build
the other one is from the "Show live issues" option (Preferences -> General)
Disabling "Show live issues" removes one occurence of the report.
I had this option off previously; I guess when I installed the new XCode this option got reset (or I reset it by mistake); but I don't recall seeing this problem in previous XCode versions...?
You can also filter out "Show only issues from the lastest build" (this will only filter in the Navigator, not in the Editor)
Topic:
Developer Tools & Services
SubTopic:
Xcode
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