remove dup when type checking all files in the project on startup

ghcide/session-loader/Development/IDE/Session.hs

@@ -578,7 +578,7 @@ loadSessionWithOptions recorder SessionLoadingOptions{..} rootDir que = do
           -- Typecheck all files in the project on startup
           checkProject <- getCheckProject
           unless (null new_deps || not checkProject) $ do
-                cfps' <- liftIO $ filterM (IO.doesFileExist . fromNormalizedFilePath) (concatMap targetLocations all_targets)
+                cfps' <- liftIO $ filterM (IO.doesFileExist . fromNormalizedFilePath) (nub $ concatMap targetLocations all_targets)
                 void $ shakeEnqueue extras $ mkDelayedAction "InitialLoad" Debug $ void $ do
                     mmt <- uses GetModificationTime cfps'
                     let cs_exist = catMaybes (zipWith (<$) cfps' mmt)