Duplicate unqualified name error on unions

[gabotechs]

Describe the bug

When going through Substrait in a query with unions, where two different union-ed columns have the same name, the following error happens:

Error: type_coercion
Schema contains duplicate unqualified field name "foo(bar(tags,Utf8(""baz"")))"

This seems to be a regression that started happening in v52 and was introduced in:

• fix: Ensure column names do not change with expand_views_at_output #19019

As reverting that PR fixes the problem.

To Reproduce

Run the new test introduced in #20106

Expected behavior

The test succeeds

Additional context

No response

[kysshsy]

take

[kysshsy]

Hi @dd-annarose, feel free to take this—I'm not sure I can fix it quickly, so if you want to tackle it, please go ahead.

[nuno-faria]

@kysshsy @dd-annarose I've opened #20146, which should hopefully fix this.