#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my $data1 = [
{
    'NAME' => 'JOE DOE',
    'DATE' => '2015-05-05',
    'NUMBER' => '00001'
}
    ];

my $data2 = [
{
    'ACCOUNT1' => '1b',
    'ACCOUNT2' => '2b',
    'ACCOUNT3' => '3b',
    'ACCOUNT4' => '3d'
}
    ];

my $data3 = [
{
    'ACCOUNT5'  => '1c',
    'ACCOUNT6'  => '2c',
    'ACCOUNT7'  => '3c',
},
{
    'ACCOUNT8'  => '4c',
    'ACCOUNT9'  => '5c',
    'ACCOUNT10' => '6c'
}
    ];

my $data4 = [
{
    'NAME' => 'Anonymous Monk',
    'DATE' => '2015-06-11',
    'NUMBER' => '00005'
}
    ];

$data1 = [ ({map { %$_ } (@$data1, @$data2, @$data3, $data4)}) ];

print Dumper $data1;

__DATA__

$VAR1 = [
          {
            'ACCOUNT5' => '1c',
            'ACCOUNT3' => '3b',
            'ACCOUNT2' => '2b',
            'NUMBER' => '00001',
            'ACCOUNT7' => '3c',
            'ACCOUNT8' => '4c',
            'NAME' => 'JOE DOE',
            'ACCOUNT1' => '1b',
            'ACCOUNT6' => '2c',
            'ACCOUNT4' => '3d',
            'ACCOUNT10' => '6c',
            'ACCOUNT9' => '5c',
            'DATE' => '2015-05-05'
          }
        ];

$VAR1 = [
          {
            'ACCOUNT7' => '3c',
            'ACCOUNT3' => '3b',
            'ACCOUNT8' => '4c',
            'ACCOUNT2' => '2b',
            'ACCOUNT5' => '1c',
            'ACCOUNT4' => '3d',
            'NAME' => 'Anonymous Monk',
            'ACCOUNT6' => '2c',
            'ACCOUNT10' => '6c',
            'NUMBER' => '00005',
            'DATE' => '2015-06-11',
            'ACCOUNT9' => '5c',
            'ACCOUNT1' => '1b'
          }
        ];