Description
In CPython we're trying to add a issue matcher for the MSVC compiler but it outputs the same warning multiple times (once per file and once in the summary usually). This results in identical annotations appearing for the same matcher, same message and line number which looks a bit cluttered:
It would be great if these identical check annotations could be avoided at the matcher level.
For reference, this is the commit in vscode that added de-duplication for problemMatchers: microsoft/vscode@b08de2e