Why is Angular ag-grid appending numbers to my column headers?

I added a new column to a grid by copying and pasting an existing ColDef. (ag-grid 30.1)

Now the header adds the number 1 to the previously existing header and adds a number 2 to the new header. I don't want those numbers to appear in the header. Where are they coming from? Why is it doing that?

I had this column:

      {
        headerName: 'My Column',
        sort: 'asc',
        filter: 'agDateColumnFilter',
        filterParams: {
          maxNumConditions: 1,
          filterOptions: ['greaterThanOrEqual', 'lessThanOrEqual', 'equals', 'inRange'],
          inRangeInclusive: true
        },
        width: 240,
        valueGetter: (params: any) => new Date(params.data.myColumn),
        valueFormatter: (params: any) => format(params.value, 'P')
      }

and then I added thio column:

      {
        headerName: 'My New Column',
        sort: 'asc',
        filter: 'agDateColumnFilter',
        filterParams: {
          maxNumConditions: 1,
          filterOptions: ['greaterThanOrEqual', 'lessThanOrEqual', 'equals', 'inRange'],
          inRangeInclusive: true
        },
        width: 240,
        valueGetter: (params: any) => new Date(params.data.myNewColumn),
        valueFormatter: (params: any) => format(params.value, 'P')
      }

Instead of "My Column" and "My New Column", the headers appear as "My Column 1" and "My New Column 2".

Why is this happening to me?

When you copied and pasted the ColDef you included the sort order:

sort: 'asc',

The 1 and 2 apparently indicate that it's sorting by the one column and then by the other. It's not intuitive and I don't see it in the documentation. But if you remove that sort property from the new ColDef the numbers will disappear.