It depends on what cross drilled pattern you got. I am guessing if they are both cross-drilled, and slotted then yes they are directional. They should have a rotational arrow on them. If not you want to put them on so that the slot part that is closest to the hub touches the brake pad first.
Here is a picture:
So the right part of the rotor where the caliper is on is the front of the car, and you can see how the pattern and slot are situated. Hope that helps, but like I said most directional rotors have an arrow pointing as to how the rotation should be.
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