You could use HASHES OF ARRAYS:

use strict;
use warnings;
use Data::Dumper;

my %hoa;
while (<DATA>) {
    my ($name, $num) = split;
    push @{$hoa{$name}}, $num;
}
print Dumper(\%hoa);

__DATA__
DAVID 31
DAVID 29
DAVID 41
[download]

prints:

$VAR1 = {
          'DAVID' => [
                       '31',
                       '29',
                       '41'
                     ]
        };
[download]