## Bug description

We have an issue in which the table of users for each cohort does not contain the same number of users as the table reports.

### Example
([Source](https://app.posthog.com/insights?startEntity=%7B%22actions%22%3A%5B%5D%2C%22events%22%3A%5B%7B%22id%22%3A%22user%20signed%20up%22%2C%22type%22%3A%22events%22%2C%22order%22%3A0%2C%22name%22%3A%22user%20signed%20up%22%7D%5D%2C%22new_entity%22%3A%5B%5D%7D&returningEntity=%7B%22events%22%3A%5B%7B%22id%22%3A%22%24pageview%22%2C%22name%22%3A%22%24pageview%22%2C%22type%22%3A%22events%22%7D%5D%7D&retentionType=retention_first_time&date_to=2020-04-05T12%3A59%3A36.001Z&period=w&display=ActionsTable&properties=%5B%7B%22key%22%3A%22id%22%2C%22value%22%3A71%2C%22type%22%3A%22cohort%22%7D%2C%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%22www.posthog.com%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%2C%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%22https%3A%2F%2Fposthog.com%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%2C%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%22localhost%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%2C%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%22127.0.0.1%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%2C%7B%22key%22%3A%22%24current_url%22%2C%22value%22%3A%220.0.0.1%22%2C%22operator%22%3A%22not_icontains%22%2C%22type%22%3A%22event%22%7D%5D&insight=RETENTION))

**Table shows 6 users in cohort:**
<img width="222" alt="" src="https://user-images.githubusercontent.com/5864173/102359528-867d9500-3f76-11eb-8134-50d0adcbd5b8.png">

**Persons list shows a lot more than 6 users in cohort:**
<img width="150" alt="" src="https://user-images.githubusercontent.com/5864173/102359599-9a28fb80-3f76-11eb-9cb8-61b37ddd4d95.png">


## Expected behavior
The persons list and the retention table should match.


## How to reproduce

See description above.

## Environment

Cloud, Clickhouse.

## Additional context

Currently blocking internal personas analysis.

#### *Thank you* for your bug report – we love squashing them!

posthog/queries/test/test_retention.py
"date_to": self._date(14, hour=6),
                        RETENTION_TYPE: RETENTION_FIRST_TIME,
                        "target_entity": target_entity,
                        "returning_entity": {"id": "$pageview", "type": "events"},
                        "selected_interval": 1,
                    }
                ),
                self.team,
            )
            self.assertEqual(len(result), 0)
        def test_retention_people_paginated(self):
            for i in range(150):
                person_id = "person{}".format(i)
                person_factory(team_id=self.team.pk, distinct_ids=[person_id])
                self._create_events(
                    [
                        (person_id, self._date(0)),
                        (person_id, self._date(1)),
                        (person_id, self._date(2)),
                        (person_id, self._date(5)),
                    ]
                )
            
            result = self.client.get(
                "/api/person/retention", data={"date_to": self._date(10, hour=6), "selected_interval": 2}
            ).json()
            self.assertEqual(len(result["result"]), 100)
            second_result = self.client.get(result["next"]).json()
            self.assertEqual(len(second_result["result"]), 50)
        def test_retention_people_in_period(self):