If an antiques shop contains two unidentified amulets, rings or wands of the same type, it gives a price for each item. If the player tries to buy both, the game charges a different price for the second item.

Change it to charge the agreed price for everything.

This avoids a situation where the player could agree to pay X for some goods but actually be charged Y for them. There are others (such as asking separately about the second item or not selling it in the same transaction), but this one doesn't involve changes to the UI.

Shops with two similar unidentified amulets, ring or wands are rare, so it shouldn't matter too much how it's handled. Charging a lot of money without warning seems like quite a bad way to do it, though.