If I remember correctly, you can't add multiple cases of the same "enchantment" to an item. You can, however, add multiple "charms" with the same attribute to boost it's total.
That's corectly
But you can, so you wish for example the enchantment "Retribution Aura level 10", put on all possible equipment-items (I think only on Yewellery for this "Retribution Aura") you wearing that have enchantmentslots!
And as Raze said:
in that case all the different equipment-items that have "Level 10 Retribution Aura" enchantments gives all together a realy strong kind of enchantment of Retribution Aura!
But remeber: there are kind of enchantments you can ONLY put on Yewellery and other only on Weapons or only on Armor!
