from random import randint

a = [1, 2, 3, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
b = []

if len(a) <= 11:
    for value in a:
        while value in b:
            value = randint(1, 11)
        b.append(value)

    print b
else:
    print "A lista 'a' deve conter no máximo 11 elementos."