Originally Posted by TonyOrtiz
you only get the aura once.
Not exactly. If you are one of the two people who are carrying Stark's you get the benefit from both, but if you are one of the three teammates who does not have stark's you will only get the aura once.
Edit: My facts come from stickied FAQ thread
Q: How do item auras work together?
A: If you and a teammate both have the same item, you will be affected by the aura twice. As an example, at the start of the game you purchase Mana Manipulator. This item gives a mana regeneration to yourself and allies nearby. If you were to go with a teammate who also purchased Mana Manipulator, both of you would be affected by this aura twice.
However, if you had a third teammate that did not
have the Mana Manipulator they would only be affected by one
Note that you can be affected by the same aura at most
twice. Once if you have it, once if a teammate has it.