How to create a numpy array with a random entries that exclude one element in each index?

I have an array val of possible values (ex. val = [0, 1, 2, 3, 4, 5]) and an array A (possibly very long list) of selected values (ex. A = [2, 3, 1, 0, 2, 1, ... , 2, 3, 1, 0, 4])

Now I want to create an array B of the same length as A such that A[i] is different than B[i] for each i and entries in B are selected randomly. How to do it efficiently using numpy?