The person asking for another copy may not understand what the first one cost to get.

Requests for paperwork are made casually and answered expensively. Another copy sounds like a printer and five minutes, when in fact it can mean a fee, a trip, a wait of several weeks, or an appointment somebody has to take unpaid leave for. The asker sees a document. The holder sees the whole process again.

Before requesting one, check whether what you already hold will do, and say why you need it if it will not. If you are the one being asked, it is reasonable to explain what it involves. Most people are not unkind about this, only uninformed.