A simple check in your read loop will handle that: 
my $last_line;
while (<$fh>) {
   chomp;

   # Skip duplicates
   next if $.>1 && $_ eq $last_line;
   $last_line = $_;

   ...proceed as normal...
}

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In reply to Re: Detect Duplicated line by ikegami
in thread Detect Duplicated line by Anonymous Monk

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