Mac OS X 10.7.3 macmini4,1 b15
Run the attached test adapted from a tutorial example. Here instead of a sinlge Cat, Dog, Pig and Bird, we have plenty of each peppered all over the list. Silly but possible, two identical items.
Open the popup: if a Bird is selected, all of them will have a tick mark as if selected. The same is true for Cat and even for Pig.

All this is not applicable to, say, Metal LaF since there's no tick against item in a popup.