SYSLIB1041 Multiple GeneratedRegex attribute duplicates CS0579 compiler diagnostics

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The analyzer for RegexGenerator generates the SYSLIB1041 Multiple GeneratedRegex attribute diagnostic when there are multiple GeneratedRegexAttribute attributes

Source

However, the GeneratedRegexAttribute is declared with AllowMultiple=false, which automatically generates the CS0579 (Duplicate 'attribute' attribute) diagnostic, even without precompilation, and the error is semantically "duplicated".

This behavior seems to be general now (checked Visual Studio, Visual Studio Code, LinqPad).

I would like to clarify why this was done?

My initial assumption was to detect design-time errors on the condition that analyzers are running. However, CS0579 doesn't let you write incorrectly and now design-time errors are shown in the IDE.

Maybe I'm missing some additional uses?