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As far as I know you cannot. Although there is a trick, if you use Repora and Itade on the other one (basically different potency runes, additive and subtractive) you can proc. We tested this a week ago, that was the result. Point is, not crafting same potency enchantments. One must be crafted with Repora (any additive), and other Itade (any subtractive).
I like the trick that @mertusta mentioned - I had not consider that.
However, I do recommend doing that or using two different enchants; I know if you use say 2 poisons it won't work. For that I tell my customers 1 poison and 1 disease. The point is: use different enchants on each weapon.
If you have two enchants of the same kind they share a cooldown. But if you have one with Disease and one with poison they can alternate. The second one can proc while the other one is on cooldown.
One other point to add, 2 infused weapons does not have an additive effect for reducing the cooldown of the same enchant. I was hoping that 2 weapons sharing the same cooldown via the same enchant would have a positive effect by using infused, but unfortunately it does not.