If anybody wonders why CalcKey renders quoted posts three times in streams, it's because we support all 12 of the quoted posts implementations -- and CalcKey now supports 3 of these (but not the method we finally agreed on for the fediverse in the FEP)
-- and this is in the activity:
"_misskey_quote": "https://calckey.social/notes/9emuzqxarz",
"quoteUri": "https://calckey.social/notes/9emuzqxarz",
"quoteUrl": "https://calckey.social/notes/9emuzqxarz",
#
Fixed. No need to file a bug.