[Bug] - union_by_name=true raise un error with same column names but different case

[Raul-rp]

When we have several Excel sheets to read, union data by column name raise an error when it finds the same column name with different case.
Example:
Sheet1 with "costcenter" column name and Sheet2 with "CostCenter" column name.
Error :

Tip: Standardise column names so : Transform header to lowercase and replace spaces with ‘_’.
"Cost Center" = "cost_center"

[RaulRoPer]

Additionally, when you find two columns with the same name in the same spreadsheet, number the second and subsequent ones as follows: header, header_1, header_2, etc.
Standardisation (lower case) and incremental numbering of headings would be the definitive solution.

[redraiment]

This is an excellent idea! Thank you for the feedback.