Can seborehhic keratosis lesions be two different colors?

Sure: They usually start as small, rough bumps, then slowly thicken and get a warty surface. Most are tan or brown and can be multiple shades. They have a waxy, "pasted on" appearance...they look like a dab of warm, brown candle wax on the skin. There are some skin lesions, especially smooth moles, with various pigments which should be checked, especially if very dark/black suggesting melanoma.