Have you tried printing Dumper \@data after you populate $data2? It seems you aren't creating a copy of the hash. To do that, you'd need something like

for my $href ( @data ) {
    my $copy_ref = { %$href };
    delete $copy_ref->{sex};
    push @{ $data2->{$href->{sex}} }, $copy_ref;
}
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Or, you can construct the target hash on the fly:

for my $href (@data) {
    push @{ $data3->{ $href->{sex} } },
         { map 'sex' eq $_ ? () : ( $_ => $href->{$_} ), keys %$href }
+;
}
[download]