**Describe what's wrong**

Query with rollup using same selected field name as the name of underlying column reports structure mismatch

**Does it reproduce on recent release?**

yes

**How to reproduce**

`21.9.2.17`

```sql
CREATE TABLE test
(
    `d` DateTime,
    `a` LowCardinality(String),
    `b` UInt64
)
ENGINE = MergeTree
PARTITION BY toDate(d)
ORDER BY d;

SELECT *
FROM (
    SELECT
        a,
        max((d, b)).2 AS value
    FROM test
    GROUP BY rollup(a)
)
WHERE a <> '';
```

**Expected behavior**

This used to return an ok result on v21.8

**Error message and/or stacktrace**

> Code: 352. DB::Exception: Block structure mismatch in (columns with identical name must have identical structure) stream: different columns:
> notEquals(a, '') LowCardinality(UInt8) ColumnLowCardinality(size = 0, UInt8(size = 0), ColumnUnique(size = 1, UInt8(size = 1)))
> notEquals(a, '') LowCardinality(UInt8) Const(size = 0, ColumnLowCardinality(size = 1, UInt8(size = 1), ColumnUnique(size = 2, UInt8(size = 2)))). (AMBIGUOUS_COLUMN_NAME) (version 21.9.2.17 (official build))



{
    
    
    std::vector<const WindowDescription *> windows_sorted;
    for (const auto & [_, w] : query_analyzer->windowDescriptions())
        windows_sorted.push_back(&w);
    std::sort(windows_sorted.begin(), windows_sorted.end(), windowDescriptionComparator);
    const Settings & settings = context->getSettingsRef();
    for (size_t i = 0; i < windows_sorted.size(); ++i)
    {
        const auto & w = *windows_sorted[i];
        
        
        
        
        if (!w.full_sort_description.empty() && (i == 0 || !sortIsPrefix(w, *windows_sorted[i - 1])))
        {
            auto partial_sorting = std::make_unique<PartialSortingStep>(
                query_plan.getCurrentDataStream(),
                w.full_sort_description,
                0 ,