Here's tye's solution. It took some time for me to get it through the chatterbox, even though the idea isn't really complicated. It uses a different interface then I do in the parent post.

my %hash;
OBJ: for my $obj ( @objects ) {
    my $fingerprint = $fingerprint{$obj};
    my $class = \@{$hash{$fingerprint}}
    for( @$class ) {
        if( same($obj,$_->[0] ) {
            push @$_, $obj;
            next OBJ:
        }
    }
    push @$class, [ $obj ]
}
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