$owo = "c:/scripts/owo.txt";

open(FILE,"<$owo") || die $!;           # read file
my @list = keys %{{map{$_,1} <FILE>}};  # remove duplicates
close(FILE);

open(FILE,">$owo") || die $!;           # write file
foreach (@list) { chomp; print FILE "$_\n"; }
close(FILE);