Bug: Sheet-scoped defined names are clobbered in v3.1
Here is a script that demonstrates a difference between version 3.0 and version 3.1: test_oppenpyxl.py
Results with version 3.0.10: test_3.0.10.xlsx
Results with version 3.1.0b1: test_3.1.0b1.xlsx
The problem is that sheet-scoped names are overwritten in v3.1, while in 3.0 it was possible to have the same name in different sheets, if it was scoped to that sheet.