add test for setitem from duplicate axis
- [x] closes #34034
- [ ] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Thanks @CloseChoice for the PR. lgtm. can you move the test to pandas\tests\indexing\test_loc.py > Thanks @CloseChoice for the PR. lgtm. can you move the test to pandas\tests\indexing\test_loc.py

Done. Thanks @CloseChoice! 