Everyone knows that one of the most popular discussions in game chat is "Does this stack with that" and often the conversation throws different points of view and a lot of, I think unneeded speculation.
When you click an item on your person, there could be an entry that refers to how it stacks.
Example :
Necklace of Health (where no other +CON item is being worn)
Constitution +2
Necklace of Health #1 (where another +4 CON item is being worn)
Constitution +2
Necklace of Health #2 (where another +2 CON item is being worn)
Constitution +4
Necklace of Health (where another +2 CON item is being worn)
Constitution +2
Necklace of Health (where another +2 CON item is being worn)
Constitution +2
::Stacking::
Black = No other item worn that stacks
Orange = Another item is worn but as the bonus is the same, no penalty occurs
Red = Another item is worn and this item takes priority
Purple = Another item is worn and this item does not take priority
This way if anyone wears an item they know which item takes priority