#! perl -slw
use strict;
use Data::Dump qw[ pp ]; $Data::Dump::WIDTH = 50;

$/ = '';

my %hash;
while( <DATA> ) {
    my %subhash;
    for my $line ( split "\n" ) {
        my( $key, $value ) = split /\s+:\s+/, $line;
        $subhash{ $key } = $value;
    }
    $hash{ $subhash{ FullName } } = \%subhash;
}

##pp \%hash;

for my $primaryKey ( keys %hash ) {
    print "$primaryKey:";
    for my $subKey ( keys %{ $hash{ $primaryKey } } ) {
        print "\t$subKey => $hash{ $primaryKey }{ $subKey }";
    }
}

__DATA__
FullName        : User1
Home Address        : 111 address lane
Phone            : 555-555-5555

FullName        : User2
Home Address        : 222 address lane 2
Phone            : 777-777-7777
[download]

Gives:

c:\test>junk7
User1:
        Phone => 555-555-5555
        Home Address => 111 address lane
        FullName => User1
User2:
        Phone => 777-777-7777
        Home Address => 222 address lane 2
        FullName => User2
[download]