As example I have such code:
DataTable table = new DataTable("Name");
table.Columns.Add("CASESENSITIVE", typeof(string));
table.Columns.Add("casesensitive", typeof(string));
table.Rows.Add("Indocin", "David");
table.Rows.Add("Enebrel", "Sam");
var wb = new XLWorkbook();
wb.Worksheets.Add(table);
wb.SaveAs("Excel.xlsx");
When I open just created file I see alert: "Excel found unreadable content in Excel.xlsx ...."
If I confirm this alert excel automaticaly add "2" for "casesensitive" column.
How solve this problem?