Or, you can switch between two states of your loop, one looking for the first line, and the second looking for the next line:

my $state = 0;
foreach my $line (<TF>){
  if($state){
    # do whatever you need with the "next" line
    $state = 0;
  } else {
    # do what you normally do
    if($next_line_needed){
      $state = 1;
    }
  }
}
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