Sentinel 2: already contains a band with the name

I am working on a Sentinel 2 data to extract abundance of a plant species by using spectral unmixing method. I have a valid csv file but could not move to next step since I always met the problem ‘the product … already contains a band with name of …’. I know there are many people met this problem. But it seems no one worked on Sentinel 2 data. Hope someone could tell me how to solve the problem. Thanks a lot!