One way to do it
# We are modifying the $/ variable, so we limit the scope
# by adding some {} around the code
{
  local $/ = '';
  $^I      = '.bak';  # See man perl and the -i switch for that trick
  @ARGV    = ('data.txt');
  while (<>) {
    # The order is not important, so we sort the fields to
    # obtain a unique id
    $sorted = join ':', sort split /\s+/; 
    print if (! $seen{$sorted}++ );
  }
}

[download]

HTH
Update : add comments to the code
--
zejames

In reply to Re: to avoid redundacy in a file by zejames
in thread to avoid redundacy in a file by Anonymous Monk

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