This small program should help you. Use Data::Dumper when in doubt.

use Data::Dumper;
use strict;
my @output = (1,2,3);
my $addr = 'x';
my %results;

push @{$results{$addr}},[@output];

@output = (4,5);
$addr = 'y';
push @{$results{$addr}},[@output];

@output = (1,4,7,9,11);
$addr = 'x';
push @{$results{$addr}},[@output];
print Dumper(\%results);

my $sum;
foreach my $addr (keys %results){
    my $array_ref = $results{$addr};
    foreach my $inner_array_ref (@{$array_ref}){
    $sum += scalar @{$inner_array_ref};
    }
}
print $sum;
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