[schoen]

I didn't think we were allowed to even potentially change the order, so I used

  awk '{if (!c[$0]) { print }; c[$0] = 1 }'

[rando832]

Oh ya, I shouldn't have said answer, because uniq is not a way to the answer, just something I naturally reached for while trying to figure out an answer.

[_druu]

    awk '!a[$0]++' faces.txt

is a touch shorter ^^

[schoen]

That's the same approach used by the challenge's original creator (in the GitHub link above). It's a clever solution!