Why does tuple(set([1,“a”,“b”,“c”,“z”,“f”])) == tuple(set([“a”,“b”,“c”,“z”,“f”,1])) 85% of the time with hash randomization enabled?

Question

Given Zero Piraeus\' answer to another question, we have that

x = tuple(set([1, \"a\", \"b\", \"c\", \"z\", \"f\"]))
y = tuple(set([\"a\", \"b\", \"c\", \"z\