**How to reproduce**

CH version: `20.5.2 revision 54435` (latest on `apt` at the moment). Cannot reproduce on `20.4.5`, so it's a regression.

Table:

```sql
create table repro_hits (
    date Date,
    metric Float64
) engine=MergeTree() order by date
```

Query:

```sql
SELECT
    date as period,
    1 as having_check,
    min(date) as period_start,
    addDays(max(date), 1) as period_end,
    dateDiff('second', period_start, period_end) as total_duration,
    sum(metric) as metric_
FROM repro_hits
GROUP BY period
having having_check != -1
```

**Error message and/or stacktrace**
```
Received exception from server (version 20.5.2):
Code: 179. DB::Exception: Received from localhost:9000. DB::Exception: Different expressions with the same alias period_start:
min(date) AS period_start
and
date AS period_start
.
```

The error goes away if I opt out of optimization with `SETTINGS enable_optimize_predicate_expression = 0`.
modified.push_back(group_key);
            continue;
        }
        if (auto * group_key_ident = group_key->as<ASTIdentifier>())
        {
            if (group_by_keys_data.key_names.count(group_key_ident->shortName()))
                modified.push_back(group_key);
            continue;
        }
        else
        {
            if (group_by_keys_data.key_names.count(group_key->getColumnName()))
                modified.push_back(group_key);
        }
    }
    
    grp_by->children = modified;
}
void optimizeAggregateFunctionsOfGroupByKeys(ASTSelectQuery * select_query)
{
    if (!select_query->groupBy())
        return;
    auto grp_by = select_query->groupBy();
    auto & group_keys = grp_by->children;
    GroupByKeysInfo group_by_keys_data = getGroupByKeysInfo(group_keys);
    auto select = select_query->select();
    SelectAggregateFunctionOfGroupByKeysVisitor::Data visitor_data{group_by_keys_data.key_names};
    SelectAggregateFunctionOfGroupByKeysVisitor(visitor_data).visit(select);
}
void optimizeDuplicatesInOrderBy(const ASTSelectQuery * select_query)