fix(rag):Fix document deduplication logic

[wangiii]

Summary

After the knowledge base hybrid retrieval selection weight is set, the recalled content is an empty array.

Tip

Close issue syntax: Fixes #<issue number> or Resolves #<issue number>, see documentation for more details.

Screenshots

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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[crazywoola]

Please see this pr as well #10931

[wangiii]

Please see this pr as well #10931另请参阅此公关 #10931

OK