When a wall is already in your favorites and you try to add it again, right now you just get a message saying its already in your favorites. But you dont get to know which collection you have it in. If you have a lot of collections this can be tedious to search for.

So instead of just the message, maybe it should be something like "Already in favorites. Go to collection? OK/Cancel".
Or if you tried to put it in XYZ and it is in ABC: "Already in collection ABC. Shift to XYZ? Yes/No"