To be asking whether passives stack or not, you should just look at the description of the item

If the item shows an unique passive e.g. those from Trinity Force, these passives will not stack BUT all the other stats outside the unique passive will

Other items to compare with are Bloodthirster bonus attack, Warmogs bonus health, Archangels staff bonus ability power passive, ... Altough it's better to choose different items instead of stacking one and the same.

To be asking whether passives stack or not, you should just look at the description of the item

If the item shows an unique passive e.g. those from Trinity Force, these passives will not stack BUT all the other stats outside the unique passive will

Other items with stackable passives with are Bloodthirster bonus attack, Warmogs bonus health, Archangels staff bonus ability power passive, ... Altough it's better to choose different items instead of stacking one and the same.