Look displays piles of items twice
Using the look command on a pile of multiple different items will show the same information twice. The exact behavior varies depending on which message buffer is used:
Two-line buffer:
As soon as you move the look cursor over a stack of items, you get a "You see the following items" message with a more prompt. Upon exiting the list of items, you get the same message with another more prompt. After exiting the list of items a second time, you are finally able to proceed.
Endless scrolling buffer:
Same behavior, but without more prompts. This gives the impression that the key used to exit the list of items didn't work the first time (if you are watching closely you can see that the list was opened a second time).