As docs say it's impossible to add two menu items to NSPopUpButton if they both have the same title. I was trying to add menu items to [popupButton menu], but with no luck. I was also trying to create a new menu, add items to it and then use [popupButton setMenu:newMenu], but no. Menu always display only one item per name.
But I know it should be possible, if you try to create a smart playlist in iTunes, you could select "Playlist" from the left popup button, "=" from the middle, and the right one will hold menu items for every playlist in iTunes EVEN if they have the same title. So how do they do it?
I had the exact problem and it was solved easily. Instead of using NSPopUpButton methods such as –addItemWithTitle: to manipulate the button items, I added an NSArrayController and added the items into the array controller instead. Then I used the bindings to bind the controller and the popup button and now it shows items with same titles.
To do the bindings: