That gives you one copy of each distinct line. The OP wanted only the lines that appear exactly once. It could be done with uniq -c and grep and cut, but it gets to the point that you just want to do it in Perl. Gar. Should have double-checked that -u option. Good answer.
Caution: Contents may have been coded under pressure.

In reply to Re^2: removing non-duplicates by Roy Johnson
in thread removing non-duplicates by Anonymous Monk

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