UNION ALL with ORDER BY and duplicate projection fails sanity checker

### Describe the bug

A query that should run successfully fails during planning.

### To Reproduce

This can easily be reproduced in `datafusion-cli` by running:
```sql
CREATE TABLE t (x INTEGER);
(SELECT x, x as __x FROM t) UNION ALL (SELECT x, x as __x FROM t) ORDER BY __x;
```

The query seems perfectly valid, but it currently errors during planning with:
```
SortExec: expr=[__x@1 ASC NULLS LAST], preserve_partitioning=[false]
ProjectionExec: expr=[x@0 as x, x@0 as __x]
DataSourceExec: partitions=1, partition_sizes=[0]

SortExec: expr=[__x@1 ASC NULLS LAST], preserve_partitioning=[false]
ProjectionExec: expr=[x@0 as x, x@0 as __x]
DataSourceExec: partitions=1, partition_sizes=[0]

Error: Execution plan does not satisfy required ordering: [__x@1 ASC NULLS LAST].
Child-0 order: [[x@0 ASC NULLS LAST]]
```

### Expected behavior

The query runs without errors.

### Additional context

We encountered this when attempting to inject projections into user queries.