In this situation to avoid any misunderstanding one should call the the prescriber to verify the quantity.
When Creating a false document, making changes into an already existing document, or fraudulently signing a document has been identified this will be consider as forgery.
In the given case the shopkeeper was concern about forgery because the amount of beneficiary written in prescription is different from normal quantity provided.
In this situation, it is better to call the prescriber to check the quantity asked to avoid forgery.
Learn more about forgery, here:
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