You can scramble some fields from the Document Properties in the Settings menu. However, that will scramble all values in the field, no matter who has logged in.
If you do need to show ClientB data, but you don't want to show its name, you will have to create a different dimension where the scrambled, hardcoded name is in the script, since you don't know who's going to log in, and therefore you need as many combinations as possible users... Cumbersome... It would be easier instead creating one document per client, so each one has its corresponding customer name scrambled or not.
But you can aggregate all competitors values and set them as "Others" if you want to reduce data but keep comparing to the rest of the competitors as a whole.
Hope that gives you an idea.