Why are my incisions still very dark after upper and lower blepharoplasty two weeks post-op?

You are extremely early from surgery.  You require more time to heal.  However to truly understand what is going on, there is not true substitute for a consultation.  That said, a photograph is helpful.

We need to see some pictures.  You may have some dark scabs still present which will make the incision look dark.  There can be some hyperpigmentation which can occur in darker skinned people, but it would be unusual for that to occur this early in the healing.  Try cleaning the wound first to see if there is any scab still there.

Darkening or redness of the surgical incision is normal two weeks after surgery.  You are very early in the healing process. The extent of this will vary from patient to patient. There are studies that show it typically takes seven months to a year for a surgical scar to fade.  You should however notice a significant improvement to your appearance over the weeks. You are correct to avoid direct UV light on your incisions as they heal.  I would avoid using makeup on your incisions until your surgeon gives you the clearance to do so.