NARS Duo Eyeshadow ($35.00 for 0.08 oz.) include two shades in the brand’s updated formulation. You can read my overview of the formula here. My personal favorites: Alhambra, Isolde, Kauai, Surabaya, Underworld, and Silk Road.
Note: The single eyeshadows received a more noticeable price drop (from $24 to $19) but the duo eyeshadows could be priced better (from $36 to $35) given that they were reduced in size.