**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))



throw Exception(
                        "Window functions does not support processing from WithMergeableStateAfterAggregation",
                        ErrorCodes::NOT_IMPLEMENTED);
            }
            else if (expressions.need_aggregate)
            {
                executeExpression(query_plan, expressions.before_window,
                    "Before window functions");
                executeWindow(query_plan);
                executeExpression(query_plan, expressions.before_order_by, "Before ORDER BY");
                executeDistinct(query_plan, true, expressions.selected_columns, true);
            }
            else
            {
                if (query_analyzer->hasWindow())
                {
                    executeWindow(query_plan);
                    executeExpression(query_plan, expressions.before_order_by, "Before ORDER BY");
                    executeDistinct(query_plan, true, expressions.selected_columns, true);
                }
                else
                {
                    
                    
                }
            }
            if (expressions.has_order_by)
            {
                /** If there is an ORDER BY for distributed query processing,
                  *  but there is no aggregation, then on the remote servers ORDER BY was made