Django distinct()不返回不同的值

我有一个 Session 模型如下:

class Session(models.Model):  
    user = models.ForeignKey(User, null=True, blank=True, on_delete=models.CASCADE, related_name="sessions")
    flavor = models.ForeignKey(Flavor, null=True, blank=True, on_delete=models.CASCADE, related_name="sessions")
    ....

我正在尝试运行一个查询:

sessions = Session.objects.all().values('flavor__pk', 'user__pk').distinct()

但是当我打印sessions对象时,我得到了:

<QuerySet [{'user__pk': 14544, 'flavor__pk': 1}, {'user__pk': 14544, 'flavor__pk': 1}, {'user__pk': None, 'flavor__pk': 30}, {'user__pk': 193, 'flavor__pk': 30}, '...(remaining elements truncated)...']>

仔细看,前两个条目是完全相同的 {'user__pk': 14544, 'flavor__pk': 1}