When you use a non-scalar (array or hash element) to hold a filehandle, you have to change your use of the diamond operator to readline:

    readline( $nbdc_filehandles[$index] );
    readline( $nbdc_filehandles[$index] );
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In some places, it's possible to disambiguate the use of a non-scalar filehandle using an anonymous block. For example, when using one as an indirect object for printing:

print { $arrayOfFileHandles[ $n } } 'some data';
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