>>468
並びが変化してもいいなら
s = {(xx, yy) for xx, yy in zip(x, y)}
x[:] = [xy[0] for xy in s]
y[:] = [xy[1] for xy in s]

並びを維持するなら
import collections
d = collections.OrderedDict(zip(zip(x, y), x))
x[:] = [xy[0] for xy in d.keys()]
y[:] = [xy[1] for xy in d.keys()]