#!/usr/bin/perl
use warnings;
use strict;

my @data = map {
    my %h;
    @h{qw{ ID Name Number CODE }} = @$_;
    \%h
} ['1212', 'JOE',   'XY1',  '6'],
  ['1212', '',      'XY1', '10'],
  ['4456', 'MARIA', 'TYX',  '6'],
  ['4456', '',      'TYX', '10'],
  ['8765', 'JEAN',  'HPO',  '6'];

my %name;
for my $d (@data) {
    $name{ $d->{ID} } = $d->{Name} if length $d->{Name};
}

my @new;
my %used;
for my $d (grep ! length $_->{Name}, @data) {
    push @new, { %$d, Name => $name{ $d->{ID} } };
    undef $used{ $name{ $d->{ID} } };
}

for my $d (@data) {
    push @new, $d if length $d->{Name} && ! exists $used{ $d->{Name} };
}

use Data::Dumper; print Dumper \@new;