I inherited an Excel sheet from my previous worker. The sheet has data organised in a lot of columns. For the heading of these columns, repeated values/texts are somehow prevented, but I don't know how (it's not via data validation) and would like to get rid of that. For example, I have a column with the heading "Data". If I try to add more columns with the same heading "Data", it get's automatically changed to "Data2", Data3" etc.
Thanks to you both. It is/was indeed a table, and converting to range solves the problem.
The issue with a table in this case is that I have a lot of reporting figures/columns which repeat every year. It would be very tedious to add the year in every column, instead the year is written above all the headings for a certain year (and so the columns all have the same heading).
I will check now if everything still works the intended way despite the data not being in a table.