BUG:

[cs-ranbi]

BUG:

[Aloqeely]

Thanks for the report! The problem is caused because your DataFrame index did not have a name so it gets set a default name of index when using to_json(orient="table"), but you also have another column with the name index, so 2 index fields were saved.

You can fix this issue by renaming your index column or by setting a name for the actual index using df.rename_axis

PRs to fix this are welcome if they don't complicate the logic too much.

[taranarmo]

take

[taranarmo]

I made this case to fail on check whether index.name is in columns names as the easiest solution. The others would change the names of user's columns or invent other generic names of nameless index.