[ENH] Support aggregate queries with duplicate references to the same `COUNT(DISTINCT expr)` expression

[andygrove]

Is your feature request related to a problem? Please describe.

See the following tests:

• test_multi_agg_count_no_group_by_dupe_distinct
• test_agg_count

Describe the solution you'd like Enable these tests

Describe alternatives you've considered None

Additional context None