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In TW1, there was a helpful prompt to let you know you had already read a book.

Is there such a thing for diagrams, so I don't buy the same one twice?
Diagrams are never "read," they have to be in your inventory to be used so just check if you have them.
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Tally: Diagrams are never "read," they have to be in your inventory to be used so just check if you have them.
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But what about the actual books? Have weight, so more than likely need to be sold after. Would be nice to be able to have a *Already Read* indicator.