my @x;
my $curr = '';
my @curr;
foreach my $ref (@$matrix_ref)
{
    my $k = $ref->[0] . $ref->[1];
    unless ($curr eq $k)
    {
        push @x, [ @curr ] if @curr;

        @curr = @$ref;
        $curr = $k;

        next;
    }

    push @curr, $ref->[2];
}
push @x, [ @curr ];

use CGI qw( :all );

$html_str = table( map { Tr( td( $_ ) ) } @x );