Bug with Nametags and Villager Trading

So I was playing around with villager trading a moment ago, and at some point, one of my librarians started trading me nametags. All fine to that point.

Trades:
Stuff - Enchanted Book - Enchanted Book - Nametag

But when I went back from the nametag, the book texture was overlain by the nametag texture. This only applied to the enchanted books, as soon as I went back to other items, the nametag was gone. When I then went forward to the enchanted books again, the textures were back to normal.