I haven't done a counter in ages:). Would this help?

#!/usr/bin/perl -slw

use strict;

my %count;
my(@dates) = (
    9.1.11, 
    9.2.11,
    9.3.11,
    9.4.11,
    9.5.11
);
foreach my $batch_dates (@dates) {
    ++$count{$_} foreach (@dates);
    sleep 1;
    print $count{$batch_dates};
}
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Update: I added List::MoreUtils for a unique counter:

#!/usr/bin/perl -slw

use strict;
use List::MoreUtils qw(uniq);

my %count;
my (@nums) = uniq 9.2.11, 9.2.11, 9.2.11, 9.4.11, 9.5.11;
foreach my $num (@nums) {
    ++$count{$_} foreach  (@nums);
    sleep 1;
    print $count{$num};
}
[download]