It works, the only problem is this line:

if (exists $file1_data{$key}) {
       if ($file1_data{$key} ne $value) { # ensure val's didn't change
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I don't need to ensure vals don't change. I need to write different arrays which maintains the order of elements, even if they're different. I played around this line for a while, but I'm not able to change it. Any suggestions?