Don't you want a loop around this block

# while (@label_list) {
     $row_data{'LABEL'} = shift @label_list;
     $row_data{'URL'} = shift @url_list;

     push( @loop_data, \%rowdata );
# }
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Though I think it is easier to construct @loop_data during your loop over then hash keys instead of creating two lists in the loop and then looping over their elements.