If your value is hashable this will work:
>>> [dict(y) for y in set(tuple(x.items()) for x in d)]
[{'y': 4, 'x': 3}, {'y': 2, 'x': 1}]
EDIT:
I tried it with no duplicates and it seemed to work fine
>>> d = [{'x':1, 'y':2}, {'x':3, 'y':4}]
>>> [dict(y) for y in set(tuple(x.items()) for x in d)]
[{'y': 4, 'x': 3}, {'y': 2, 'x': 1}]
and
>>> d = [{'x':1,'y':2}]
>>> [dict(y) for y in set(tuple(x.items()) for x in d)]
[{'y': 2, 'x': 1}]
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…