Cart price rule except products with special price

I want to know if I can do the next scenario for a cart rule:
I created a code(20% of subtotal) that is applied for a subtotal greater than 100 Euros and except 2 cateogries(for example 10, 20). Can I add a new rule(beside this) to except from this rule the products that also have a special price? What I want is to do this discount for subtotal 100 except that are products from category 10 and 20 and all products that already have a discout(special price) The site is made in Magento 1.9. Thank you!