**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))



{
            query_analyzer.makeWindowDescriptions(chain.getLastActions());
            query_analyzer.appendWindowFunctionsArguments(chain, only_types || !first_stage);
            
            
            for (const auto & x : chain.getLastActions()->getNamesAndTypesList())
            {
                query_analyzer.columns_after_window.push_back(x);
            }
            
            
            
            for (const auto & [_, w] : query_analyzer.window_descriptions)
            {
                for (const auto & f : w.window_functions)
                {
                    query_analyzer.columns_after_window.push_back(
                        {f.column_name, f.aggregate_function->getReturnType()});
                }
            }
            before_window = chain.getLastActions();
            finalize_chain(chain);
            auto & step = chain.lastStep(query_analyzer.columns_after_window);