Textract extract 2 columns of QUANTITY type data. What would be the best way to detect which is the good one?

Question

I'm using AWS Textract with AnalyzeExpense to extract data from P.O.

But sometime, P.O. have "QTY ORDERED" and "QTY SHIPPED" and both are detected as QUANTITY. So I end up with 2 possible QUANTITY data source.

I would like to know if there is some common rules or pattern that would make sure I'm always using the correct columns in general.

I could easily parse and look at the LabelDetection, or do some calculation to check if QUANTITY * UNIT_PRICE = PRICE (if UNIT_PRICE & PRICE are detected) but as I'm dealing with different P.O. from different suppliers, i would like to get some hint to find a golden rule that would match most cases.