Actually, it's this:
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is used to block out possible sources of interference in the code. For example, if you tested
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, and got
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, you wouldn't know if it was
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,
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,
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, or
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that triggered the faces. But if you used
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, you could more easily figure out where the
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and
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are.
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is used to block out symbols in the code as well. Whereas guessing
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against
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would return
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, guessing
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against the same code would return
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, making it a bit more helpful in determining the contents of the first two cells.
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is used to determine if you're guessing the right symbols. If you guessed
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, and got
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, and you knew the
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,
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, and
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were correct, you wouldn't know if the 4th symbol was
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,
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,
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,
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, or what. But guessing
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gives a bit more info, since it'll return 4 faces if there are no repeats, and 3 if there are repeats.
Just a note:
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takes precedence over
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. So guessing
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against
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would return
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, with
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corresponding to the first
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matching to the
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, the first
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corresponding the the second
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matching to the
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, and the other
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corresponding to the
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.
And also, the person needs to guess the exact code to win, not just get
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. Otherwise, the game would be over after someone guessed
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.