Rule for selecting all products in cart where catalogue price equals selling price (for a promotion)

I would like add a promotion which affects only products where the selling price equals the catalogue price. I am trying to figure out how to make a rule for this. We want to set a fixed discount amount if the total of purchases is above 100,-, but it should only count products without another discount. Anyone knows how to do this?

E.g. In cart we have:

item 1. price: 75,- catalogue price: 75,-
item 2. prce: 50,- catalogue price: 50,-
Total value: 125,- (total value of items without discount: 125,-)
APPLY DISCOUNT: TRUE

item 1. price: 75,- catalogue price: 75,-
item 2. price: 50,- catalogue price: 60,-
Total: 125 (total value of items without discount: 75,-)
APPLY DISCOUNT: FALSE

item 1. price: 75,- catalogue price: 75,-
item 2. price: 50,- catalogue price: 50,-
item 2. price: 50,- catalogue price: 60,-
Total: 175 (total value of items without discount: 125,-)
APPLY DISCOUNT: TRUE

Is this possible?