Step 1: Choose Any Sunglasses/Eyeglasses on Lenskart and Click on

Step 2: Choose any Other Eyeglasses/Sunglasses by clicking on Buy More Products

Step 3: Choose Another Sunglasses/Eyeglasses on Lenskart and Click on

Step 4: On The Cart Page You will See Both Products Added

Step 5: On The Cart Page You will See Discount Codes Box

Step 6: Type Coupon Code Buy1get1 on the Coupon Code Box and Apply Code

You will see The product with lower price/similar is Discounted.