When trading costs two items, the second requested item will disappear after unloading the chunk where the villager is.

If, for instance, you have a Librarian villager offering an 'Infinity I' enchanted book for a book and 31 emeralds, once the chunks are unloaded, the requested emeralds will disappear and thus, you will be able to trade books for Infinity I without emeralds / second requested item.