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Depends on your LSAT/GPA, and where you are applying. E.g., if low 170s and 4.0ish and applying to HYS, yes addendum. If same stats and applying to T6 and below, who cares. Etc.
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There is no situation in which two Ws deserves an addendum or explanation of any kind, especially for someone with a 3.9. Don’t write one.
I wouldn’t.