CVS: Buy One Get One FREE Diet Coke CouponJanuary 5, 2011 by Mitchell Wischmann This post may contain a link to an affiliate. See my disclosure policy for more information. Wow! CVS is offering up a new buy one get one FREE Diet Coke or Caffeine Free Diet Coke (20 oz bottle) coupon! Hurry and print this one before it runs out of prints!