**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`.
{
    const auto & order_by = select_query->orderBy();
    if (!order_by)
        return;
    std::unordered_set<String> prev_keys;
    ASTs modified;
    modified.reserve(order_by->children.size());
    for (auto & order_by_element : order_by->children)
    {
        
        ASTPtr & name_or_function = order_by_element->children[0];
        if (name_or_function->as<ASTFunction>())
        {
            if (!prev_keys.empty())
            {
                RedundantFunctionsInOrderByVisitor::Data data{prev_keys, context};
                RedundantFunctionsInOrderByVisitor(data).visit(name_or_function);
                if (data.redundant)
                    continue;
            }
        }
        
        if (auto * identifier = name_or_function->as<ASTIdentifier>())
            prev_keys.emplace(getIdentifierName(identifier));
        modified.push_back(order_by_element);
    }
    if (modified.size() < order_by->children.size())
        order_by->children = std::move(modified);
}
void optimizeLimitBy(const ASTSelectQuery * select_query)