This piece of code:

@timestamps = sort (@timestamps);
$unique[0] = $timestamps[0];
foreach my $stamp(@timestamps) {
  unless ($stamp eq $unique[$counter]) {
    push (@unique, $stamp);
    $counter++;
  }
}
[download]

looks like you're trying to copy the unique elements of @timestamps into @unique. I'd do that like this:

my %unique;
@unique{@timestamps} = ();
my @unique = keys %unique;
[download]

Blessed Be
The Pixel