This line is definitiely problematic:

$hash{$counter}{'url'} = push @{$fields},$url
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...because push has a return value of the number of elements in @{$fields} after $url is pushed. I'm not exactly sure what you're after, but I know that you're misusing push, and getting unexpected results.

I suspect you're after something more like this:

push @{ $hash{$counter}{url} }, $url;
[download]