use strict;
use warnings;

use Spreadsheet::Read;

my $ss = ReadData ("4_19_10_Zrc01a-2.xls");
my $s  = $ss->[1];

my %max;
foreach my $r (1 .. $s->{maxrow}) {
    my ($A, $B) = ($s->{cell}[1][$r], $s->{cell}[2][$r]);
    $max{$A} //= $B;
    $max{$A} < $B and $max{$A} = $B;
    }

print "$_\t$max{$_}\n" for sort { $a <=> $b } keys %max;


##</code><code>##

$ perl test.pl
1       4
2       7
3       10
$