No need to use an array:

use strict;
my ($saved_name, $number) = split /\s/, <DATA>;
print "$saved_name\t$number\n";
while (<DATA>) {
    (my $name, $number) = split /\s+/, $_;
    if ($saved_name eq $name) {
        print '      ';
    }
    else {
        print $name;
    }
    print "\t$number\n";
    $saved_name=$name;
}

__DATA__
GEORGE 21
GEORGE 45
NICK   12
PETER  27
JIM    18
JIM    87
CHRIS  33
[download]

Output:

GEORGE 21
       45
NICK   12
PETER  27
JIM    18
       87
CHRIS  33
[download]