Menu DUPLICATE: Control and extra field to know from which Document was made

Hi all,
I don’t know if many of you have this issue with Customers… But in my case we do have.
An Invoice/Quotation was done on January for item A. On that time the Company was on NO VAT.
After few months lets say now in August the Company is no on VAT 5% and for some reason the user decided to DUPLICATE that invoice done on January using the same ITEM A changing only the Dates… Of course the System will redo the calcs…

My point here is to have an extra field that will be filled when DUPLICATE is used so we can know from which Invoice or Quotation the DUPLICATE was done and inform users or prevent them from copying TAXING…