get() excepts MultipleObjectsReturned on a field marked unique

I have a field on a model that's marked unique:

uid = models.CharField(max_length=255, blan开发者_运维问答k=False, null=False, unique=True)

I'm trying to use get() to get the one Profile that should match this uid:

UserProfile.objects.get(uid=fr_uid)

The problem is that this line raises a MultipleObjectsReturned exception for some users even though that field is marked unique:

Line: return self.get_query_set().get(*args, **kwargs)

Local variables:
clone   [<Profile: John Smith>, <Profile: John Smith>]
num     2

If I get the same profile from a shell, I only get one back:

Profile.objects.get(uid='abc1234')
<Profile: John Smith>

Now I understand that I should probably be handling a MultipleObjectsReturned exception anyway, but I cannot understand why I would ever get multiple objects returned on a field marked unique.

Have you made any modifications to the manager? Or are you doing any sort of filtering on the queryset before calling get() on it? In particular, using Q objects for OR boolean searches can often result in the same object being returned multiple times. If that's the case, call distinct() on the queryset before get().