Use manual discount code along with automatic using cartDiscountCodesUpdate api

I am using cartDiscountCodesUpdate api to add discount code in the cart. I have set one automatic discount code in the cart. Besides that I want to use one more manual discount code in the cart. When I pass manual discount code in api, it’s not getting applicable. I am getting applicable: false in response. Please help me with this to figure it out asap.

Automatic discount code is getting applied. I want to add another manual code with cartDiscountCodesUpdate api.